mx5: Use explicit clock gate names

Use clock gate definitions having names showing clearly the gated clock instead
of names giving only a register field index.

Signed-off-by: Benoît Thébaudeau <benoit.thebaudeau@advansee.com>
Cc: Stefano Babic <sbabic@denx.de>
diff --git a/drivers/video/ipu_common.c b/drivers/video/ipu_common.c
index cc8f881..0f2d113 100644
--- a/drivers/video/ipu_common.c
+++ b/drivers/video/ipu_common.c
@@ -214,7 +214,7 @@
 #if defined(CONFIG_MX51) || defined(CONFIG_MX53)
 	.enable_reg = (u32 *)(CCM_BASE_ADDR +
 		offsetof(struct mxc_ccm_reg, CCGR5)),
-	.enable_shift = MXC_CCM_CCGR5_CG5_OFFSET,
+	.enable_shift = MXC_CCM_CCGR5_IPU_OFFSET,
 #else
 	.enable_reg = (u32 *)(CCM_BASE_ADDR +
 		offsetof(struct mxc_ccm_reg, CCGR3)),