clk: qcom: add REGULATOR as dependency for QCOM_GDSC

QCOM_GDSC has dependency on the core regulator framework.
Define REGULATOR as dependency on the QCOM_GDSC Kconfig
entry.

Change-Id: I714036e9dc4e49acbe29a85abf9f511f6f5a4b3e
Signed-off-by: Osvaldo Banuelos <osvaldob@codeaurora.org>