Telephony: Decode SPN from RuimRecords properly

To address issues with incorrect encoding scheme programmed
in some commercial CSIM cards, the decoded SPN is checked to
have characters in printable ASCII range. If not, they are
decoded with ENCODING_GSM_7BIT_ALPHABET scheme.

Change-Id: I938f4ac7d2c4cee6732c3abad1be7db7395276ad
CRs-Fixed: 483975
(cherry picked from commit cf50334109bd6259445beb3345b6da038a5b7927)
(cherry picked from commit 1f37671a2c611971102a1c99da3da9893adc4247)
(cherry picked from commit 084a2d80cb4f6c4130900a3e9017f1927bb0b52e)