ACPI: SBS: remove unused const variable 'SMBUS_PEC'

drivers/acpi/sbshc.h:18:17: warning:
 SMBUS_PEC defined but not used [-Wunused-const-variable=]

SMBUS_PEC is never used since introduction in
commit 91087dfa ("ACPI: SBS: Split host
controller (ACPI0001) from SBS driver (ACPI0002)"),
so just remove it.
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/sbshc.h

@@ -15,8 +15,6 @@ enum acpi_smb_protocol {
 	SMBUS_BLOCK_PROCESS_CALL = 0xd,
 };
 
-static const u8 SMBUS_PEC = 0x80;
-
 enum acpi_sbs_device_addr {
 	ACPI_SBS_CHARGER = 0x9,
 	ACPI_SBS_MANAGER = 0xa,