mmc: msm_sdcc: Fix issue with msmsdcc_enable()

Due to the recent commit 68338b, any pending runtime PM
work (runtime suspend/resume request) is not getting
cancelled before enabling the host for a new request.
This results in a possibility for suspend work to happen
in parallel while processing any active SD/MMC command.

CRs-fixed: 305399
Signed-off-by: Sahitya Tummala <stummala@codeaurora.org>