imx: mx7: enable CONFIG_FSL_CLK

This commit "677f970bc62a661690b3431543d5a5d5e682ba70" introduce a new
macro "CONFIG_FSL_CLK" that get_clocks() should not be limited by ESDHC.

But that patch missed to enable it for i.MX7. THis patch enables
CONFIG_FSL_CLK to let get_clocks work.

Signed-off-by: Peng Fan <Peng.Fan@freescale.com>
Cc: Adrian Alonso <aalonso@freescale.com>
Cc: Stefano Babic <sbabic@denx.de>
Cc: Fabio Estevam <fabio.estevam@freescale.com>

include/configs/mx7_common.h

@@ -36,6 +36,8 @@
 #define CONFIG_DISPLAY_CPUINFO
 #define CONFIG_DISPLAY_BOARDINFO
 
+#define CONFIG_FSL_CLK
+
 #define CONFIG_LOADADDR                 0x80800000
 #define CONFIG_SYS_TEXT_BASE            0x87800000