armv8: layerscape: get rid of smc_call()

armv8: layerscape: get rid of smc_call()

There are two different implementations to do a secure monitor call:
smc_call() and arm_smccc_smc(). The former is defined in fwcall.c and
seems to be an ad-hoc implementation. The latter is imported from linux.

smc_call() is also only available if CONFIG_ARMV8_PSCI is not defined.
This makes it impossible to have both PSCI calls and PSCI implementation
in one u-boot build. The layerscape SoC code decide at runtime via
check_psci() if there is a PSCI support. Therefore, this is a
prerequisite patch to add PSCI implementation support for the layerscape
SoCs.

Note, for the TFA part, this is only compile time tested with
(ls1028ardb_tfa_defconfig).

Signed-off-by: Michael Walle <michael@walle.cc>
[Rebased]
Signed-off-by: Priyanka Jain <priyanka.jain@nxp.com>