arch/x86/acpigen: acpigen buffer size fix

In function definition of acpigen_write_byte_buffer, buffer size written
using acpigen_emit_byte gives wrong results in generated AML code for
buffer size greater than one.

Write buffer size using acpigen_write_integer as per ACPI spec 5.0
section 20.2.5.4 BufferOp.

Change-Id: I0dcb25b24a1b4b592ad820c95f7c2df67a016594
Signed-off-by: Naresh G Solanki <naresh.solanki@intel.com>
Reviewed-on: https://review.coreboot.org/17444
Reviewed-by: Furquan Shaikh <furquan@google.com>
Tested-by: build bot (Jenkins)
Reviewed-by: Nico Huber <nico.h@gmx.de>

src/arch/x86/acpigen.c

@@ -1143,7 +1143,7 @@ void acpigen_write_byte_buffer(uint8_t *arr, uint8_t size)
 
 	acpigen_emit_byte(BUFFER_OP);
 	acpigen_write_len_f();
-	acpigen_emit_byte(size);
+	acpigen_write_byte(size);
 
 	for (i = 0; i < size; i++)
 		acpigen_emit_byte(arr[i]);