mmc: core: propagate removable attribute to driver core

Userspace can use this to distinguish hotpluggable mmc devices such as
sdcards from non-hotpluggable ones such as eMMC.
One example is the lsblk tool from util-linux.

Note that dev_set_removable() is not related to GENHD_FL_REMOVABLE which
is not applicable as per the comment in drivers/mmc/core/block.c

Link: https://github.com/util-linux/util-linux/issues/2379


Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Reviewed-by: Avri Altman <avri.altman@wdc.com>
Link: https://lore.kernel.org/r/20230725-mmc-removable-v1-1-b2e0c4f18e6d@weissschuh.net


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