intel/i945: Call fixup_i945_errata() only for mobile version

Per Mobile Intel ® 945 Express Chipset Family - Specification Update
Document Number: 309220-013 (page 15), the power saving optimization
Erratum is for Mobile Intel ® 945 Express Chipset family.

So rename 'fixup_i945_errata()' to 'fixup_i945gm_errata()' and apply
that function only for I945GM.

Change-Id: I2656021b791061b4c22c0b252656a340de76ae5e
Signed-off-by: Elyes HAOUAS <ehaouas@noos.fr>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/37188
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
diff --git a/src/northbridge/intel/i945/errata.c b/src/northbridge/intel/i945/errata.c
index 2b9b941..4d8b999 100644
--- a/src/northbridge/intel/i945/errata.c
+++ b/src/northbridge/intel/i945/errata.c
@@ -17,7 +17,7 @@
 #include "i945.h"
 #include "raminit.h"
 
-int fixup_i945_errata(void)
+int fixup_i945gm_errata(void)
 {
 	u32 reg32;