ARM: mmp: Drop unneeded select of COMMON_CLK

Support for Marvell MMP ARMv5 platforms depends on ARCH_MULTI_V5, and
thus on ARCH_MULTIPLATFORM.
As the latter selects COMMON_CLK, there is no need for MACH_MMP_DT to
select COMMON_CLK.

Link: https://lore.kernel.org/r/20200505150722.1575-11-geert+renesas@glider.be


Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Lubomir Rintel <lkundrak@v3.sk>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Lubomir Rintel <lkundrak@v3.sk>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>