counter: stm32-timer-cnt: Add check for clk_enable()

Add check for the return value of clk_enable() in order to catch the
potential exception.

Fixes: c5b84255 ("counter: stm32-timer-cnt: add power management support")
Fixes: ad29937e ("counter: Add STM32 Timer quadrature encoder")
Signed-off-by: Jiasheng Jiang <jiashengjiangcool@gmail.com>
Link: https://lore.kernel.org/r/20241104191825.40155-1-jiashengjiangcool@gmail.com


Signed-off-by: William Breathitt Gray <wbg@kernel.org>