video: fbdev: nvidia: Fix set but not used warnings

Fix warnings by deleting unused code. The register reads are
kept as it is unknown if there are any hidden side-effects.

v2:
- Update subject (Lee)

Signed-off-by: Sam Ravnborg <[e-mail]>
Acked-by: Thomas Zimmermann <[e-mail]>
Cc: Antonino Daplas <[e-mail]>
Cc: [e-mail]
Cc: Lee Jones <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

drivers/video/fbdev/nvidia/nv_setup.c

···
 }
 void NVWriteAttr(struct nvidia_par *par, u8 index, u8 value)
 {
-	volatile u8 tmp;
 
-	tmp = VGA_RD08(par->PCIO, par->IOBase + 0x0a);
+	VGA_RD08(par->PCIO, par->IOBase + 0x0a);
 	if (par->paletteEnabled)
 		index &= ~0x20;
 	else
···
 }
 u8 NVReadAttr(struct nvidia_par *par, u8 index)
 {
-	volatile u8 tmp;
-
-	tmp = VGA_RD08(par->PCIO, par->IOBase + 0x0a);
+	VGA_RD08(par->PCIO, par->IOBase + 0x0a);
 	if (par->paletteEnabled)
 		index &= ~0x20;
 	else