viafb: reduce viafb_set_iga_path usage

The result of viafb_set_iga_path can change after init only in the
hotplug ioctl. So we can move it there rather than doing it always
when a new mode is set. The setup during init is done via a call
from the init chip funtion.
This change enables a stable mapping between the old device scheme
and a new more powerfull one.

Signed-off-by: Florian Tobias Schandinat <[e-mail]>
Cc: Joseph Chan <[e-mail]>

drivers/video/via/hw.c

···
 		via_write_reg(VIASR, i, VPIT.SR[i - 1]);
 
 	viafb_write_reg_mask(0x15, VIASR, 0xA2, 0xA2);
-	viafb_set_iga_path();
 
 	/* Write CRTC */
 	viafb_fill_crtc_timing(crt_timing, vmode_tbl, video_bpp / 8, IGA1);

drivers/video/via/ioctl.c

···
 				viafb_CRT_ON = 0;
 				viafb_LCD_ON = 0;
 				viafb_DeviceStatus = DVI_Device;
+				viafb_set_iga_path();
 				return viafb_DeviceStatus;
 			}
 			status = 1;
···
 		viafb_LCD_ON = 0;
 
 		viafb_DeviceStatus = CRT_Device;
+		viafb_set_iga_path();
 		return viafb_DeviceStatus;
 	}