arm64: smccc: add support for SMCCCv1.2 x0-x17 registers

arm64: smccc: add support for SMCCCv1.2 x0-x17 registers

add support for x0-x17 registers used by the SMC calls

In SMCCC v1.2 [1] arguments are passed in registers x1-x17.
Results are returned in x0-x17.

This work is inspired from the following kernel commit:

arm64: smccc: Add support for SMCCCv1.2 extended input/output registers

[1]: https://documentation-service.arm.com/static/5f8edaeff86e16515cdbe4c6?token=

Signed-off-by: Abdellatif El Khlifi <abdellatif.elkhlifi@arm.com>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Reviewed-by: Jens Wiklander <jens.wiklander@linaro.org>
Reviewed-by: Simon Glass <sjg@chromium.org>
Cc: Tom Rini <trini@konsulko.com>