imx-common: wrap boot_mode_apply with CONFIG_CMD_BMODE

boot_mode_apply should be applied only with CONFIG_CMD_BMODE enabled.

Signed-off-by: Peng Fan <Peng.Fan@freescale.com>
Cc: Stefano Babic <sbabic@denx.de>
diff --git a/arch/arm/imx-common/init.c b/arch/arm/imx-common/init.c
index 56d5010..058cf79 100644
--- a/arch/arm/imx-common/init.c
+++ b/arch/arm/imx-common/init.c
@@ -103,6 +103,7 @@
 	writel(val, &src_regs->scr);
 }
 
+#ifdef CONFIG_CMD_BMODE
 void boot_mode_apply(unsigned cfg_val)
 {
 	unsigned reg;
@@ -115,3 +116,4 @@
 		reg &= ~(1 << 28);
 	writel(reg, &psrc->gpr10);
 }
+#endif