Fix sparse build warning:

drivers/mmc/host/sdhci-msm.c:1888:6: warning:
 symbol 'sdhci_msm_dump_vendor_regs' was not declared. Should it be static?
Signed-off-by: Hulk Robot <hulkci@huawei.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Link: https://lore.kernel.org/r/20200702020347.77214-1-weiyongjun1@huawei.comSigned-off-by: Ulf Hansson <ulf.hansson@linaro.org>