check-sr-results: bump ir revision to 1.2

IR v1.1 is no longer available for certification since publication of the
SRS v2.0 (Oct '22) and the 6 months transition period has closed (Apr '23).

We can thus issue only IR v1.2 certifications from the IR v1.x family for
now; bump the detected version accordingly.

Signed-off-by: Vincent Stehlé <vincent.stehle@arm.com>