refactor(stm32mp1): update tamp_bkpr return type

tamp_bkpr() returns a register address. So use uintptr_t instead of
uin32_t.

Signed-off-by: Nicolas Toromanoff <nicolas.toromanoff@foss.st.com>
Change-Id: I5eddfa525465313dadfec18d128248a968ba74e2
3 files changed