clk: qcom: gcc-sdmshrike: Add the clk structure definition

The GCC clock driver is currently using the clk structure
without defining it. Add the definition in order to resolve
the compilation issue.

Change-Id: Ie49989624569ec6398ce29625c370ce1959e8202
Signed-off-by: Deepak Katragadda <dkatraga@codeaurora.org>