Revert "mmc: mmc: Attempt to flush cache before reset"

This reverts commit 437db4c6.

In current design, mmc_cmdq_thread() context will claim host and
mmc_blk_cmdq_complete or mmc_blk_cmdq_err contexts will release
the host. The upstream change added mmc_flush_cache() to mmc_reset()
which is used in mmc_blk_cmdq_err and resulting in deadlock.

schedule()
__mmc_claim_host() >> claimed by mmc-cmdqd
mmc_interrupt_hpi()
mmc_flush_cache()
mmc_reset()
mmc_cmdq_hw_reset()
mmc_blk_cmdq_reset.constprop.43()
mmc_blk_cmdq_reset_all(inline)
mmc_blk_cmdq_err()
mmc_cmdq_error_work()

So we cannot claim host within completion or error contexts.

Change-Id: I98b528104795ce217fc8ed52d822b34d20cdb00c
Signed-off-by: Sayali Lokhande <sayalil@codeaurora.org>