acpi: Mark struct acpi_rsdp as packed

At present the size of this struct is too large on 64-bit machines.
Annotate it with __packed to fix this.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/include/acpi/acpi_table.h b/include/acpi/acpi_table.h
index b8b1f133..8ef19ad 100644
--- a/include/acpi/acpi_table.h
+++ b/include/acpi/acpi_table.h
@@ -36,7 +36,7 @@
  * RSDP (Root System Description Pointer)
  * Note: ACPI 1.0 didn't have length, xsdt_address, and ext_checksum
  */
-struct acpi_rsdp {
+struct __packed acpi_rsdp {
 	char signature[8];	/* RSDP signature */
 	u8 checksum;		/* Checksum of the first 20 bytes */
 	char oem_id[6];		/* OEM ID */