wcnss: Check the return value of clk_set_parent() when sample clock

The return value of clk_set_parent() should be checked when sample WCNSS
TOP AHB clock on WCNSS WDOG bite, otherwise it might be pointing to an
old parent that happens to be enabled.

Change-Id: I8b6ef12fa9f1b9bf6869fcfb7441148ee9d7c84c
Signed-off-by: Yue Ma <yuem@codeaurora.org>