mmc: sdhci-msm: enable compile-testing on !ARM

There seems to be no particular reason to only test for ARM, so allow
for build-testing on other platforms to increase coverage.

Build-tested on x86 with allyesconfig.

Signed-off-by: Alex Dewar <alex.dewar90@gmail.com>
Link: https://lore.kernel.org/r/20200824171854.406157-1-alex.dewar90@gmail.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>