Some SIMs contain an EFspn with the contents all set to 'filler'
characters, e.g. 0xFF. We mistakenly do not handle these strings
correctly.
Aug 8 11:40:00 mx31tt01 daemon.info ofonod[622]: Aux: >
AT+CRSM=176,28486,0,0,17\r
Aug 8 11:40:00 mx31tt01 daemon.info ofonod[622]: Aux: < \r\n+CRSM:
144,0,
FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF\r\n\r\nOK\r\n
Aug 8 11:40:00 mx31tt01 daemon.debug ofonod[622]:
drivers/atmodem/sim.c:at_crsm_read_cb() crsm_read_cb: 90, 00, 17
Aug 8 11:40:00 mx31tt01 daemon.debug ofonod[622]:
src/simfs.c:sim_fs_op_read_block_cb() bufoff: 0, dataoff: 0, tocopy: 17
Aug 8 11:40:00 mx31tt01 daemon.err ofonod[622]: EFspn read
successfully, but couldn't parse
+ case 0xff: /* Special case of empty string */
+ num_chars = 0;
+ ucs2_offset = 0;
+ offset = 0;
+ break;
+