ARM: 8783/1: NOMMU: Extend check for VBAR support

ARMv8R adds support for VBAR and updates ID_PFR1 with the new filed
Sec_frac (bits [23:20]):

Security fractional field. When the Security field is 0000, determines
the support for features from the ARMv7 Security Extensions. Permitted
values are:

0000 No features from the ARMv7 Security Extensions are implemented.
     This value is not supported in ARMv8 if ID_PFR1 bits [7:4] are zero.

0001 The implementation includes the VBAR, and the TCR.PD0 and TCR.PD1
     bits.

0010 As for 0001, plus the ability to access Secure or Non-secure
     physical memory is supported.

All other values are reserved.

This field is only valid when ID_PFR1[7:4] == 0, otherwise it holds
the value 0000.

Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

arch/arm/mm/nommu.c

@@ -53,7 +53,8 @@ static inline bool security_extensions_enabled(void)
 {
 	/* Check CPUID Identification Scheme before ID_PFR1 read */
 	if ((read_cpuid_id() & 0x000f0000) == 0x000f0000)
-		return !!cpuid_feature_extract(CPUID_EXT_PFR1, 4);
+		return cpuid_feature_extract(CPUID_EXT_PFR1, 4) ||
+			cpuid_feature_extract(CPUID_EXT_PFR1, 20);
 	return 0;
 }