UPSTREAM: arm64/sme: Fix NULL check after kzalloc

Fix following coccicheck error:
./arch/arm64/kernel/process.c:322:2-23: alloc with no test, possible model on line 326

Here should be dst->thread.sve_state.

Fixes: 8bd7f91c ("arm64/sme: Implement traps and syscall handling for SME")
Signed-off-by: Wan Jiabing <wanjiabing@vivo.com>
Reviwed-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20220426113054.630983-1-wanjiabing@vivo.com


Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
(cherry picked from commit 2e29b997)
Signed-off-by: Will Deacon <willdeacon@google.com>
Bug: 233587962
Bug: 233588291
Change-Id: Ic9048ae5ef32e6ccb305836a349977c9fbc6f6d6