doc: Fix typos

Fix typos/wording in various files in doc/.

Signed-off-by: Wolfgang Wallner <wolfgang.wallner@br-automation.com>
Reviewed-by: E Shattow <e@freeshell.de>

doc/develop/devicetree/control.rst

@@ -288,7 +288,7 @@ The full devicetree is available to U-Boot proper, but normally only a subset
 Using several DTBs in the SPL (SPL_MULTI_DTB_FIT Kconfig option)
 ----------------------------------------------------------------
 In some rare cases it is desirable to let SPL be able to select one DTB among
-many. This usually not very useful as the DTB for the SPL is small and usually
+many. This is usually not very useful as the DTB for the SPL is small and usually
 fits several platforms. However the DTB sometimes include information that do
 work on several platforms (like IO tuning parameters).
 In this case it is possible to use SPL_MULTI_DTB_FIT Kconfig option. This option

doc/develop/driver-model/fdt-fixup.rst

@@ -45,7 +45,7 @@ An additional problem with the device tree in U-Boot is that it is read-only,
 and the current mechanisms don't allow easy manipulation of the device tree
 after the driver model has been initialized. While migrating to a live device
 tree (at least after the relocation) would greatly simplify the solution of
-this problem, it is a non-negligible task to implement it, an a interim
+this problem, it is a non-negligible task to implement it, an ad interim
 solution is needed to address the problem at least in the medium-term.
 
 Hence, we propose a solution to this problem by offering a board-specific

doc/develop/testing.rst

@@ -28,7 +28,7 @@ run. Type this::
 
     make tcheck
 
-You can also run a selection tests in parallel with::
+You can also run a selection of tests in parallel with::
 
     make pcheck
 
@@ -39,7 +39,7 @@ are run. See :doc:`pytest/usage` for more information.
 Sandbox
 -------
 U-Boot can be built as a user-space application (e.g. for Linux). This
-allows test to be executed without needing target hardware. The 'sandbox'
+allows tests to be executed without needing target hardware. The 'sandbox'
 target provides this feature and it is widely used in tests.
 
 See :doc:`tests_sandbox` for more information.

doc/develop/trace.rst

@@ -354,7 +354,7 @@ Writing Out Trace Data
 ----------------------
 
 Once the trace data is in an output buffer in memory there are various ways
-to transmit it to the host. Notably you can use tftput to send the data
+to transmit it to the host. Notably you can use tftpput to send the data
 over a network link::
 
     fakegocmd=trace pause; usb start; set autoload n; bootp;