Some register were only set in aty_init() which is not called on resume.  I
added the aty_resume_chip() function to reset those registers on resume.

Susped-to-ram now works on a HP Omnibook 6000 with acpi_sleep=s3_bios.
Signed-off-by: NVille Syrjala <syrjala@sci.fi>
Cc: "Antonino A. Daplas" <adaplas@pol.net>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>