ACPI: tables: Allow BGRT to be overridden

Thinkpad T Series expose a malformed BGRT table with Version field set
to 0. This fact prevents bootsplashes (as Plymouth) to correctly show
the manufacturer logo. This patch permits to override malformed BGRT
table with a correct one defined by the user.

Signed-off-by: Andrea Oliveri <oliveriandrea@gmail.com>
[ rjw: Subject ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/tables.c

@@ -490,16 +490,17 @@ static u8 __init acpi_table_checksum(u8 *buffer, u32 length)
 
 /* All but ACPI_SIG_RSDP and ACPI_SIG_FACS: */
 static const char * const table_sigs[] = {
-	ACPI_SIG_BERT, ACPI_SIG_CPEP, ACPI_SIG_ECDT, ACPI_SIG_EINJ,
-	ACPI_SIG_ERST, ACPI_SIG_HEST, ACPI_SIG_MADT, ACPI_SIG_MSCT,
-	ACPI_SIG_SBST, ACPI_SIG_SLIT, ACPI_SIG_SRAT, ACPI_SIG_ASF,
-	ACPI_SIG_BOOT, ACPI_SIG_DBGP, ACPI_SIG_DMAR, ACPI_SIG_HPET,
-	ACPI_SIG_IBFT, ACPI_SIG_IVRS, ACPI_SIG_MCFG, ACPI_SIG_MCHI,
-	ACPI_SIG_SLIC, ACPI_SIG_SPCR, ACPI_SIG_SPMI, ACPI_SIG_TCPA,
-	ACPI_SIG_UEFI, ACPI_SIG_WAET, ACPI_SIG_WDAT, ACPI_SIG_WDDT,
-	ACPI_SIG_WDRT, ACPI_SIG_DSDT, ACPI_SIG_FADT, ACPI_SIG_PSDT,
-	ACPI_SIG_RSDT, ACPI_SIG_XSDT, ACPI_SIG_SSDT, ACPI_SIG_IORT,
-	ACPI_SIG_NFIT, ACPI_SIG_HMAT, ACPI_SIG_PPTT, NULL };
+	ACPI_SIG_BERT, ACPI_SIG_BGRT, ACPI_SIG_CPEP, ACPI_SIG_ECDT,
+	ACPI_SIG_EINJ, ACPI_SIG_ERST, ACPI_SIG_HEST, ACPI_SIG_MADT,
+	ACPI_SIG_MSCT, ACPI_SIG_SBST, ACPI_SIG_SLIT, ACPI_SIG_SRAT,
+	ACPI_SIG_ASF,  ACPI_SIG_BOOT, ACPI_SIG_DBGP, ACPI_SIG_DMAR,
+	ACPI_SIG_HPET, ACPI_SIG_IBFT, ACPI_SIG_IVRS, ACPI_SIG_MCFG,
+	ACPI_SIG_MCHI, ACPI_SIG_SLIC, ACPI_SIG_SPCR, ACPI_SIG_SPMI,
+	ACPI_SIG_TCPA, ACPI_SIG_UEFI, ACPI_SIG_WAET, ACPI_SIG_WDAT,
+	ACPI_SIG_WDDT, ACPI_SIG_WDRT, ACPI_SIG_DSDT, ACPI_SIG_FADT,
+	ACPI_SIG_PSDT, ACPI_SIG_RSDT, ACPI_SIG_XSDT, ACPI_SIG_SSDT,
+	ACPI_SIG_IORT, ACPI_SIG_NFIT, ACPI_SIG_HMAT, ACPI_SIG_PPTT,
+	NULL };
 
 #define ACPI_HEADER_SIZE sizeof(struct acpi_table_header)