drm/nouveau/bios: fix offset calculation for BMPv1 bioses

drm/nouveau/bios: fix offset calculation for BMPv1 bioses

commit 5d2f4767c4eacab351b8450b0de4d3261fe1a957 upstream.

The only BIOS on record that needs the 14 offset has a bios major
version 2 but BMP version 1.01. Another bunch of BIOSes that need the 18
offset have BMP version 2.01 or 5.01 or higher. So instead of looking at the
bios major version, look at the BMP version. BIOSes with BMP version 0
do not contain a detectable script, so always return 0 for them.

See https://bugs.freedesktop.org/show_bug.cgi?id=68835

Reported-by: Mauro Molinari <mauromol@tiscali.it>
Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>