ARM: dts: msm: Enable clock_a7 as the driver for mdmfermium cpu clocks

Add clock_cpu and cpufreq node entries in mdmfermium dtsi to specifiy
the speed-bin settings and different cpu frequencies, also to enable
clock_a7 as the driver for mdmfermium cpu clocks.

Change-Id: I5f1c290368bb3c1d431548c48845a713b6c99a5d
Signed-off-by: Jaydeep Sen <jsen@codeaurora.org>