x86/mce/intel: Use MCG_BANKCNT_MASK instead of 0xff

Use the predefined MCG_BANKCNT_MASK macro instead of the hardcoded
0xff to mask the bank number bits.

No functional changes intended.

Signed-off-by: Qiuxu Zhuo <qiuxu.zhuo@intel.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Reviewed-by: Nikolay Borisov <nik.borisov@suse.com>
Reviewed-by: Sohil Mehta <sohil.mehta@intel.com>
Link: https://lore.kernel.org/r/20241025024602.24318-3-qiuxu.zhuo@intel.com

Author: qzhuo2

arch/x86/kernel/cpu/mce/intel.c

@@ -94,7 +94,7 @@ static int cmci_supported(int *banks)
 	if (!boot_cpu_has(X86_FEATURE_APIC) || lapic_get_maxlvt() < 6)
 		return 0;
 	rdmsrl(MSR_IA32_MCG_CAP, cap);
-	*banks = min_t(unsigned, MAX_NR_BANKS, cap & 0xff);
+	*banks = min_t(unsigned, MAX_NR_BANKS, cap & MCG_BANKCNT_MASK);
 	return !!(cap & MCG_CMCI_P);
 }