Ignore case in ONS when setting roaming

When home vs roaming is decided, roaming could have been set
instead of home because isSameNamedOperators checked
if spn is equal to onsl and onss so something like this could
happen:
SPN=carrier vs ONS=carrier => home
SPN=Carrier vs ONS=carrier => roaming

Ignore case.

Bug: 26321337
Change-Id: I92a7b8b1ebdc22968a2856a6694d487607546303