stm32mp: split stm32mp_io_setup function

A new static function boot_mmc is created to simplify code maintenance
of stm32mp_io_setup.

Change-Id: I5c416e567e7e174fb1c2b435925a983c9c55fc40
Signed-off-by: Yann Gautier <yann.gautier@st.com>
1 file changed