cosmetic: refactor db_bind_imsi() as db_bind_text()

There are more uses for a generalized db_bind_text(), and in an upcoming patch
there will be similar functions like db_bind_int().

Also, add argument param_name, optionally indicating a named SQL parameter to
bind to, which will be used in subsequent patches. So far, all callers pass
NULL to yield previous db_bind_imsi() behavior of binding to the first param.

Change-Id: I87bc46a23a724677e8319d6a4b032976b7ba9394
3 files changed