Add global variable sdhc_per_clk for arm/powerpc

The QorIQ 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.
This patch is to add another global variable sdhc_per_clk for
periperhal clock, which provides higher frequency and is required
to be used for SD UHS and eMMC HS200/HS400 speed modes.

Signed-off-by: Yangbo Lu <yangbo.lu@nxp.com>
diff --git a/arch/powerpc/include/asm/global_data.h b/arch/powerpc/include/asm/global_data.h
index b6e4dd6..1620fba 100644
--- a/arch/powerpc/include/asm/global_data.h
+++ b/arch/powerpc/include/asm/global_data.h
@@ -14,6 +14,7 @@
 struct arch_global_data {
 #if defined(CONFIG_FSL_ESDHC)
 	u32 sdhc_clk;
+	u32 sdhc_per_clk;
 #if defined(CONFIG_FSL_ESDHC_ADAPTER_IDENT)
 	u8 sdhc_adapter;
 #endif