[PATCH] drm/mgag200: fix build on alpha arch

[Sam Ravnborg]

When building imgag200 for the alpha architecture it fails like this:
mgag200_drv.c:233:9: error: implicit declaration of function ‘vmalloc’
  233 |  bios = vmalloc(size);
      |         ^~~~~~~
      |         kmalloc

When building for other architectures vmalloc.h is pulled in via some
other header file - for example asm-generic/io.h.
Use an explicit include of vmalloc.h to fix the build.

Signed-off-by: Sam Ravnborg <sam at ravnborg.org>
Fixes: e20dfd27f7aa ("drm/mgag200: Add support for G200 desktop cards")
Cc: Thomas Zimmermann <tzimmermann at suse.de>
Cc: Egbert Eich <eich at suse.com>
Cc: Takashi Iwai <tiwai at suse.de>
Cc: Lyude Paul <lyude at redhat.com>
---
I have lost track if the offending commit is on the way to upstream or
it is just in drm-misc-next. But I think it is the latter so we can
apply this to drm-misc-next.

	Sam

 drivers/gpu/drm/mgag200/mgag200_drv.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/gpu/drm/mgag200/mgag200_drv.c b/drivers/gpu/drm/mgag200/mgag200_drv.c
index 09170d46aa53..b282b0e42c2d 100644
--- a/drivers/gpu/drm/mgag200/mgag200_drv.c
+++ b/drivers/gpu/drm/mgag200/mgag200_drv.c
@@ -9,6 +9,7 @@
 #include <linux/console.h>
 #include <linux/module.h>
 #include <linux/pci.h>
+#include <linux/vmalloc.h>
 
 #include <drm/drm_drv.h>
 #include <drm/drm_file.h>
-- 
2.25.1