mmc: arm_pl180_mmci: Simplify code using dev_read_addr_ptr()

Simplify the code a bit by using dev_read_addr_ptr() instead of
dev_read_addr(). This avoids having to cast explicitly to void*.

Signed-off-by: Stephan Gerhold <stephan@gerhold.net>
Reviewed-by: Patrice Chotard <patrice.chotard@foss.st.com>
Tested-by: Patrice Chotard <patrice.chotard@foss.st.com> on stm32f769-disco
Reviewed-by: Jaehoon Chung <jh80.chung@samsung.com>