arm: cache-cp15: correct debug trace

Display in the debug trace the needed information, start and phys
address (and not the &start) in mmu_set_region_dcache_behaviour_phys,
before shift operation by MMU_SECTION_SHIFT.

For example, a debug trace for STM32MP157C-EV1 is:
mmu_set_region_dcache_behaviour_phys: start=c0000000, phys=c0000000,\
 size=10000000, option=0x1e

Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>