clk: qcom: clock-a7: Add support for MSM ZIRC

MSM ZIRC contains A7 subsystem which share a common
A7 clock tree. Therefore, enable the clock-a7 driver
on MSM ZIRC to allow controlling of the a7 clock.

Change-Id: Iba744b26e1f2bc2236a002fbe2d5d17187d2e39e
Signed-off-by: Tianyi Gou <tgou@codeaurora.org>