mmc: rename mmc_can_gpio_ro() to mmc_host_can_gpio_ro()

mmc_can_* functions sometimes relate to the card and sometimes to the host.
Make it obvious by renaming this function to include 'host'.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Link: https://lore.kernel.org/r/20250401095847.29271-12-wsa+renesas@sang-engineering.com


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