pl011.c: use nex_malloc allocator
pl011.c: use nex_malloc allocator

pl011 driver is a core code, so it should use nexus memory allocator.

Signed-off-by: Volodymyr Babchuk <07adff7e050dc3230ac0b7d9c296bbb62f4ecc95@gmail.com>
Reviewed-by: Jens Wiklander <7706914404370d7502c27a0eff493dcf491feb51@linaro.org>

pascal-brand-st-dev/optee_os,pascal-brand-st-dev/optee_os,pascal-brand-st-dev/optee_os,pascal-brand-st-dev/optee_os,pascal-brand-st-dev/optee_os