common: Simplify get_clocks() #ifdef

get_clocks is wrapped by CONFIG_FSL_CLK and CONFIG_M68K in seperate
piece code. They can be merged into one snippet.

Signed-off-by: Peng Fan <Peng.Fan@freescale.com>
Cc: Tom Rini <trini@konsulko.com>
Cc: Simon Glass <sjg@chromium.org>
Cc: Bin Meng <bmeng.cn@gmail.com>
Cc: Alexey Brodkin <abrodkin@synopsys.com>
Cc: "angelo@sysam.it" <angelo@sysam.it>
Cc: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>
Cc: Stephen Warren <swarren@nvidia.com>
Cc: "Andreas Bießmann" <andreas.devel@googlemail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Acked-by: Angelo Dureghello <angelo@sysam.it>