ARM: keystone2: Remove unsed external clocks

Remove unused external clocks and make a common definition
for all keystone platforms.

Reviewed-by: Tom Rini <trini@konsulko.com>
Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
diff --git a/arch/arm/mach-keystone/clock-k2l.c b/arch/arm/mach-keystone/clock-k2l.c
index 0bd0fd6..0004059 100644
--- a/arch/arm/mach-keystone/clock-k2l.c
+++ b/arch/arm/mach-keystone/clock-k2l.c
@@ -47,7 +47,7 @@
 			reg = KS2_ARMPLLCTL0;
 			break;
 		case DDR3_PLL:
-			ret = external_clk[ddr3_clk];
+			ret = external_clk[ddr3a_clk];
 			reg = KS2_DDR3APLLCTL0;
 			break;
 		default: