feat(plat/marvell/a3720/uart): preserve x1/x2 regs in console_a3700_core_init()

Followup changes will need function arguments in registers x0, x1 and
x2. Do not modify x1 and x2 registers and instead use scratch x3 and x4
registers for storing local variables.

Signed-off-by: Pali Rohár <pali@kernel.org>
Change-Id: I8551a802995f39128d2f4a8f8076b5bf463d0db0
1 file changed