feat(stm32mp1): add regulator framework compilation

Add required macro PLAT_NB_RDEVS in platform code, and update
platform.mk to compile regulator framework.

Change-Id: I9dc7a0a4c4f5a23d9bedda368d407612c9cd21cd
Signed-off-by: Pascal Paillet <p.paillet@st.com>
Signed-off-by: Yann Gautier <yann.gautier@foss.st.com>
2 files changed