arm64: KVM: report configured SRE value to 32-bit world

After commit b34f2bcb ("arm64: KVM: Make ICC_SRE_EL1 access return the
configured SRE value") we report SRE value to 64-bit guest, but 32-bit
one still handled as RAZ/WI what leads to funny promise we do not keep:

"GICv3: GIC: unable to set SRE (disabled at EL2), panic ahead"

Instead, return the actual value of the ICC_SRE_EL1 register that the
guest should see.

 [ Tweaked commit message - Christoffer ]
Signed-off-by: NVladimir Murzin <vladimir.murzin@arm.com>
Acked-by: NMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: NChristoffer Dall <christoffer.dall@linaro.org>

arch/arm64/kvm/sys_regs.c

@@ -1352,7 +1352,7 @@ static const struct sys_reg_desc cp15_regs[] = {
 	{ Op1( 0), CRn(10), CRm( 3), Op2( 1), access_vm_reg, NULL, c10_AMAIR1 },
 
 	/* ICC_SRE */
-	{ Op1( 0), CRn(12), CRm(12), Op2( 5), trap_raz_wi },
+	{ Op1( 0), CRn(12), CRm(12), Op2( 5), access_gic_sre },
 
 	{ Op1( 0), CRn(13), CRm( 0), Op2( 1), access_vm_reg, NULL, c13_CID },