ACPI / OSL: Mark the function acpi_table_checksum() as static

Marks the function acpi_table_checksum() as static in osl.c
because it is not used outside this file.

This eliminates the following warning in osl.c:
drivers/acpi/osl.c:547:11: warning: no previous prototype for
‘acpi_table_checksum’ [-Wmissing-prototypes]
Signed-off-by: NRashika Kheria <rashika.kheria@gmail.com>
Reviewed-by: NJosh Triplett <josh@joshtriplett.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/osl.c

@@ -540,7 +540,7 @@ static u64 acpi_tables_addr;
 static int all_tables_size;
 
 /* Copied from acpica/tbutils.c:acpi_tb_checksum() */
-u8 __init acpi_table_checksum(u8 *buffer, u32 length)
+static u8 __init acpi_table_checksum(u8 *buffer, u32 length)
 {
 	u8 sum = 0;
 	u8 *end = buffer + length;