mmc: debugfs: Add debug fs entry for mmc driver

Add debug fs entry to query eMMC and SD card errors statistics

Signed-off-by: Liangliang Lu <quic_luliang@quicinc.com>
Signed-off-by: Sayali Lokhande <quic_sayalil@quicinc.com>
Signed-off-by: Bao D. Nguyen <quic_nguyenb@quicinc.com>
Signed-off-by: Shaik Sajida Bhanu <quic_c_sbhanu@quicinc.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Link: https://lore.kernel.org/r/1653674036-21829-4-git-send-email-quic_c_sbhanu@quicinc.com


Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>