Platform: Change the HAL prototype to report status

Change the return type of tfm_spm_hal_configure_default_isolation() from
"void" to "enum tfm_plat_err_t" to report errors to caller.

Change-Id: Iadfd82e546a5141f0db1624358f09111fd7530c1
Signed-off-by: Edison Ai <edison.ai@arm.com>