refactor(stm32mp2): update display of reset reason

Update the check of reset reason management, update displayed string
aligned with reference manual (por_rstn/bor_rstn/Pin reset), add some
missing reset reason (C1RST) and reuse string to reduce the size of BL2.

Change-Id: I343a46d69bf0447cafed684eab1b2e812e08ab3a
Signed-off-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
1 file changed