From: "Luiz Fernando N. Capitulino" <lcapitulino@prefeitura.sp.gov.br>

Make HGA acceleration functions selectable in kernel config, fix these
warnings:

drivers/video/hgafb.c:452: warning: `hgafb_fillrect' defined but not used
drivers/video/hgafb.c:472: warning: `hgafb_copyarea' defined but not used
drivers/video/hgafb.c:502: warning: `hgafb_imageblit' defined but not used