mark 9020 sff/mt stable for release

i initially decided to say unstable, but the default
configuration is reliable; the only caveat is that if
you enable IOMMU, you must only be using intel graphics.

this is already documented in warn.txt files, and on
the website, so it's more than ok to call this stable.

i use one of these myself as my daily driver and it's
rock solid. i haven't had any problems with it. i also
sell these to people with libreboot. no problems.

mark it as stable, ready for a full release.

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

config/coreboot/dell9020mt-nri_12mb/target.cfg

@@ -5,4 +5,4 @@ payload_seabios_withgrub="y"
 payload_seabios_grubonly="y"
 payload_memtest="y"
 grub_scan_disk="ahci"
-status="unstable"
+status="stable"

config/coreboot/dell9020mt_12mb/target.cfg

@@ -6,4 +6,4 @@ payload_seabios_grubonly="y"
 payload_memtest="y"
 grub_scan_disk="ahci"
 release="n"
-status="unstable"
+status="stable"

config/coreboot/dell9020mtbmrc_12mb/target.cfg

@@ -6,4 +6,4 @@ payload_seabios_grubonly="y"
 payload_memtest="y"
 grub_scan_disk="ahci"
 release="n"
-status="unstable"
+status="stable"

config/coreboot/dell9020sff-nri_12mb/target.cfg

@@ -5,4 +5,4 @@ payload_seabios_withgrub="y"
 payload_seabios_grubonly="y"
 payload_memtest="y"
 grub_scan_disk="ahci"
-status="unstable"
+status="stable"

config/coreboot/dell9020sff_12mb/target.cfg

@@ -6,4 +6,4 @@ payload_seabios_grubonly="y"
 payload_memtest="y"
 grub_scan_disk="ahci"
 release="n"
-status="unstable"
+status="stable"

config/coreboot/dell9020sffbmrc_12mb/target.cfg

@@ -6,4 +6,4 @@ payload_seabios_grubonly="y"
 payload_memtest="y"
 grub_scan_disk="ahci"
 release="n"
-status="unstable"
+status="stable"