staging: r8188eu: fix warnings in rtw_pwrctrl

Refactor the code to fix following warnings:
    WARNING: Comparisons should place the constant on the right side of the test

Signed-off-by: Vihas Makwana <makvihas@gmail.com>
Link: https://lore.kernel.org/r/20220517140626.3716-3-makvihas@gmail.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>