mmc: add missing MODULE_DESCRIPTION() macros

mmc: add missing MODULE_DESCRIPTION() macros

make allmodconfig && make W=1 C=1 reports:
WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/mmc/host/of_mmc_spi.o
WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/mmc/host/tmio_mmc_core.o
WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/mmc/host/renesas_sdhi_core.o
WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/mmc/core/mmc_core.o
WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/mmc/core/pwrseq_simple.o
WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/mmc/core/pwrseq_sd8787.o
WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/mmc/core/pwrseq_emmc.o
WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/mmc/core/sdio_uart.o

Add the missing invocations of the MODULE_DESCRIPTION() macro.

Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com> # for TMIO and SDHI
Signed-off-by: Jeff Johnson <quic_jjohnson@quicinc.com>
Reviewed-by: Dragan Simic <dsimic@manjaro.org>
Link: https://lore.kernel.org/r/20240611-md-drivers-mmc-v2-1-2ef2cbcdc061@quicinc.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>