pwm: crc: Allow compilation as module and with COMPILE_TEST

The driver compiles just fine as a module. The parent driver's Kconfig
symbol already depends on X86 || COMPILE_TEST, so X86 can just be
dropped from the dependencies allowing compilation on other platforms
than x86.

Link: https://lore.kernel.org/r/20230804142707.412137-3-u.kleine-koenig@pengutronix.de
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>