grub.cfg: search a reduced list of devs/partitions

in practise, the machines we support don't have
the option of including so many disks; 8 seems like
the most reasonable default. additionally, it's
unreasonable to expect *20 partitions*

this hardcoding is done to avoid using *, which is
slow in grub on some machines (the grub kernel always
re-enumerates the devices during every operation,
without caching any of it)

yet, the hardcoding is also slow; balance it a bit
better by searching fewer permutations, but not so few
that it would likely break a lot of setups

Signed-off-by: Leah Rowe <leah@libreboot.org>

config/grub/config/grub.cfg

@@ -81,8 +81,8 @@ function try_user_config {
 }
 function search_grub {
 	echo -n "Attempting to load grub.cfg from '${1}' devices"
-	for i in 0 1 2 3 4 5 6 7 8 9 10 11; do
+	for i in 0 1 2 3 4 5 6 7 8; do
-		for part in 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20; do
+		for part in 1 2 3 4 5 6 7 8 9 10 11 12; do
 			if [ "${1}" != "nvme" ]; then
 				try_user_config "(${1}${i},${part})"
 			else
@@ -117,8 +117,8 @@ function try_isolinux_config {
 }
 function search_isolinux {
 	echo "\nAttempting to parse iso/sys/extlinux config from '${1}' devices"
-	for i in 0 1 2 3 4 5 6 7 8 9 10 11; do
+	for i in 0 1 2 3 4 5 6 7 8; do
-		for part in 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20; do
+		for part in 1 2 3 4 5 6 7 8 9 10 11 12; do
 			if [ "${1}" != "nvme" ]; then
 				try_isolinux_config "(${1}${i},${part})"
 			else
@@ -167,8 +167,8 @@ menuentry 'Load Operating System (incl. fully encrypted disks)  [o]' --hotkey='o
 
 	unset bootdev
 	for grub_disk in ${grub_scan_disk}; do
-		for i in 0 1 2 3 4 5 6 7 8 9 10 11; do
+		for i in 0 1 2 3 4 5 6 7 8; do
-			for part in 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20; do
+			for part in 1 2 3 4 5 6 7 8 9 10 11 12; do
 				if [ "${grub_disk}" = "ahci" ]; then
 					bootdev="${bootdev} (ahci${i},${part})"
 				elif [ "${grub_disk}" = "ata" ]; then