ARM: opcodes: add __ERET/__MSR_ELR_HYP instruction encoding

Enabling boot from HYP mode requires the use of some more
virt-specific instructions ("eret" and "msr elr_hyp, reg").

Add the necessary encoding to asm/opcode-virt.h.
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

arch/arm/include/asm/opcodes-virt.h

@@ -26,4 +26,14 @@
 	0xF7E08000 | (((imm16) & 0xF000) << 4) | ((imm16) & 0x0FFF)	\
 )
 
+#define __ERET	__inst_arm_thumb32(					\
+	0xE160006E,							\
+	0xF3DE8F00							\
+)
+
+#define __MSR_ELR_HYP(regnum)	__inst_arm_thumb32(			\
+	0xE12EF300 | regnum,						\
+	0xF3808E30 | (regnum << 16)					\
+)
+
 #endif /* ! __ASM_ARM_OPCODES_VIRT_H */