Arm32: MSR to SPSR needs qualification

The Arm ARM's description of MSR (ARM DDI 0406C.d section B9.3.12)
doesn't even allow for plain "SPSR" here, and while gas accepts this, it
takes it to mean SPSR_cf. Yet surely all of SPSR wants updating on this
path, not just the lowest and highest 8 bits.

Fixes: dfcffb128b ("xen/arm32: SPSR_hyp/SPSR")
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>

xen/arch/arm/arm32/entry.S

@@ -395,7 +395,7 @@ return_to_hypervisor:
         ldr r11, [sp, #UREGS_pc]
         msr ELR_hyp, r11
         ldr r11, [sp, #UREGS_cpsr]
-        msr SPSR, r11
+        msr SPSR_cxsf, r11
 #ifdef CONFIG_ARM32_HARDEN_BRANCH_PREDICTOR
         /*
          * Hardening branch predictor may require to setup a different