test: Make cmd_ut_category() static

This function is not used outside the cmd_ut file anymore, so make it
static.

Signed-off-by: Simon Glass <sjg@chromium.org>

include/test/suites.h

@@ -7,26 +7,4 @@
 #ifndef __TEST_SUITES_H__
 #define __TEST_SUITES_H__
 
-struct unit_test;
-struct unit_test_state;
-
-/**
- * cmd_ut_category() - Run a category of unit tests
- *
- * @uts: Unit-test state, which must be ready for use, i.e. ut_init_state()
- *	has been called. The caller is responsible for calling
- *	ut_uninit_state() after this function returns
- * @name:	Category name
- * @prefix:	Prefix of test name
- * @tests:	List of tests to run
- * @n_ents:	Number of tests in @tests
- * @argc:	Argument count provided. Must be >= 1. If this is 1 then all
- *		tests are run, otherwise only the one named @argv[1] is run.
- * @argv:	Arguments: argv[1] is the test to run (if @argc >= 2)
- * Return: 0 if OK, CMD_RET_FAILURE on failure
- */
-int cmd_ut_category(struct unit_test_state *uts, const char *name,
-		    const char *prefix, struct unit_test *tests, int n_ents,
-		    int argc, char *const argv[]);
-
 #endif /* __TEST_SUITES_H__ */