x86/quirks: Include linux/pnp.h for arch_pnpbios_disabled()

arch_pnpbios_disabled() is defined in architecture code on x86, but this
does not include the appropriate header, causing a warning:

arch/x86/kernel/platform-quirks.c:42:13: error: no previous prototype for 'arch_pnpbios_disabled' [-Werror=missing-prototypes]
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Alexander Lobakin <aleksander.lobakin@intel.com>
Link: https://lore.kernel.org/all/20230516193549.544673-10-arnd%40kernel.org

arch/x86/kernel/platform-quirks.c

 // SPDX-License-Identifier: GPL-2.0
 #include <linux/kernel.h>
 #include <linux/init.h>
+#include <linux/pnp.h>
 
 #include <asm/setup.h>
 #include <asm/bios_ebda.h>