mmc: rtsx: Let MMC core handle runtime PM

mmc: rtsx: Let MMC core handle runtime PM

BugLink: https://bugs.launchpad.net/bugs/1963615
Since MMC core handles runtime PM reference counting, we can avoid doing
redundant runtime PM work in the driver. That means the only thing
commit 5b4258f6721f ("misc: rtsx: rts5249 support runtime PM") misses is
to always enable runtime PM, to let its parent driver enable ASPM in the
runtime idle routine.

Fixes: 7499b529d97f ("mmc: rtsx: Use pm_runtime_{get,put}() to handle runtime PM")
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
Link: https://lore.kernel.org/r/20220216055435.2335297-1-kai.heng.feng@canonical.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit 7570fb41e450ba37bf9335fe3751fa9f502c30fa linux-next)
Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
Acked-by: Tim Gardner <tim.gardner@canonical.com>
Signed-off-by: Paolo Pisati <paolo.pisati@canonical.com>