xen/arm32: SPSR_hyp/SPSR

SPSR_hyp is not meant to be accessed from Hyp mode (EL2); accesses
trigger UNPREDICTABLE behaviour. Xen should read/write SPSR instead.
See: ARM DDI 0487D.b page G8-5993.

This fixes booting Xen/arm32 on QEMU.

Signed-off-by: Stefano Stabellini <stefano.stabellini@xilinx.com>
Reviewed-by: Julien Grall <jgrall@amazon.com>
Reviewed-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
Tested-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>

xen/arch/arm/arm32/entry.S

@@ -170,7 +170,7 @@ ENDPROC(prepare_context_from_guest)
         mrc     CP32(r11, HSR)                 /* Save exception syndrome */
         str     r11, [sp, #UREGS_hsr]
 
-        mrs     r11, SPSR_hyp
+        mrs     r11, SPSR
         str     r11, [sp, #UREGS_cpsr]
 
         /*
@@ -395,7 +395,7 @@ return_to_hypervisor:
         ldr r11, [sp, #UREGS_pc]
         msr ELR_hyp, r11
         ldr r11, [sp, #UREGS_cpsr]
-        msr SPSR_hyp, r11
+        msr SPSR, r11
 #ifdef CONFIG_ARM32_HARDEN_BRANCH_PREDICTOR
         /*
          * Hardening branch predictor may require to setup a different