ar71xx: really fix Mikrotik board detection
commit
e09da0169a08 ("ar71xx: fix Mikrotik board detection")
was generated based on testing a rb-912 board, on which detection failed.
Testing on more hardware shows something fun:
machine : MikroTik RouterBOARD 922UAGS-5HPacD
machine : Mikrotik RouterBOARD 912UAG-5HPnD
Both lowercase and uppercase are used.
So ensure we support both now ..
Fixes: e09da0169a08 ("ar71xx: fix Mikrotik board detection")
Signed-off-by: Koen Vandeputte <koen.vandeputte@ncentric.com>