m68k: add global variable sdhc_per_clk for m68k

The FSL eSDHC controller supports two reference clocks. They are
platform clock and periperhal clock. The global variable sdhc_clk
has already been used for platform clock.
ColdFire also uses eSHDC controller, as in arm and powerpc,
so adding sdhc_per_clk to arch_global_data.

Signed-off-by: Angelo Durgehello <angelo@kernel-space.org>

arch/m68k/include/asm/global_data.h

@@ -23,6 +23,9 @@ struct arch_global_data {
 #ifdef CONFIG_MCF5441x
 	unsigned long sdhc_clk;
 #endif
+#if defined(CONFIG_FSL_ESDHC)
+	u32 sdhc_per_clk;
+#endif
 };
 
 #include <asm-generic/global_data.h>