Fix restoring APIBKey registers

Instruction key A was incorrectly restored in the instruction key B
registers.

Change-Id: I4cb81ac72180442c077898509cb696c9d992eda3
Signed-off-by: Sandrine Bailleux <sandrine.bailleux@arm.com>

lib/el3_runtime/aarch64/context.S

@@ -356,7 +356,7 @@ func pauth_context_restore
 	msr	APIAKeyLo_EL1, x9
 	msr	APIAKeyHi_EL1, x10
 
-	ldp	x9, x10, [x11, #CTX_PACIAKEY_LO]
+	ldp	x9, x10, [x11, #CTX_PACIBKEY_LO]
 	msr	APIBKeyLo_EL1, x9
 	msr	APIBKeyHi_EL1, x10