target/arm: Remove writefn from TTBR0_EL3

The EL3 version of this register does not include an ASID,
and so the tlb_flush performed by vmsa_ttbr_write is not needed.

Reviewed-by: Aaron Lindsay <aaron@os.amperecomputing.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Message-id: 20181019015617.22583-2-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

target/arm/helper.c

@@ -4312,7 +4312,7 @@ static const ARMCPRegInfo el3_cp_reginfo[] = {
       .fieldoffset = offsetof(CPUARMState, cp15.mvbar) },
     { .name = "TTBR0_EL3", .state = ARM_CP_STATE_AA64,
       .opc0 = 3, .opc1 = 6, .crn = 2, .crm = 0, .opc2 = 0,
-      .access = PL3_RW, .writefn = vmsa_ttbr_write, .resetvalue = 0,
+      .access = PL3_RW, .resetvalue = 0,
       .fieldoffset = offsetof(CPUARMState, cp15.ttbr0_el[3]) },
     { .name = "TCR_EL3", .state = ARM_CP_STATE_AA64,
       .opc0 = 3, .opc1 = 6, .crn = 2, .crm = 0, .opc2 = 2,