Out of memory check fix for tee_mm_alloc
Out of memory check fix for tee_mm_alloc

This is to address issue #304 where tee_mm_alloc has an
incorrect check for out of memory condition.

Reviewed-by: Pascal Brand <0b55292d2562685bad4ce52d64f802e8f1cd299e@linaro.org>
Reviewed-by: Jens Wiklander <7706914404370d7502c27a0eff493dcf491feb51@linaro.org>
Signed-off-by: Youssef Esmat <1bfbe2c435ac91b5291b8524df1352a486d75bab@microsoft.com>

Microsoft/optee_os,pascal-brand-st-dev/optee_os,pascal-brand-st-dev/optee_os,Microsoft/optee_os,chshxi1989/optee_os,matt2048/optee_os,BreezeWu/optee_os,pascal-brand-st-dev/optee_os,matt2048/optee_os,pascal-brand-st-dev/optee_os,cedric-chaumont-st-dev/optee_os,Microsoft/optee_os,matt2048/optee_os,BreezeWu/optee_os,chshxi1989/optee_os,Microsoft/optee_os,BreezeWu/optee_os,cedric-chaumont-st-dev/optee_os,Microsoft/optee_os,chshxi1989/optee_os,BreezeWu/optee_os,chshxi1989/optee_os,BreezeWu/optee_os,chshxi1989/optee_os,cedric-chaumont-st-dev/optee_os,matt2048/optee_os,pascal-brand-st-dev/optee_os,cedric-chaumont-st-dev/optee_os