staging: most: dim2: check return value of clk_prepare_enable for PLL

staging: most: dim2: check return value of clk_prepare_enable for PLL

The return value of clk_prepare_enable() for the PLL clock is not
checked, while the same call for the MLB clock is properly checked
earlier in the function. If clk_prepare_enable() fails, the driver
continues without the PLL clock enabled, leading to undefined
hardware behavior.

Add the missing error check and disable the MLB clock on failure to
keep the cleanup consistent with the rest of the function.

Signed-off-by: Artem Lytkin <iprintercanon@gmail.com>
Link: https://patch.msgid.link/20260216201921.1788-2-iprintercanon@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>