msm: mdm: add board support for the sglte modem

The sglte modem has its own flash. The power-on
and power-off sequences are also different from
the flashless modem, and the gpios used for IPC
are different. The mdm driver supports both
types of modems.

Change-Id: Iad33a00a24b00a90f315933f659f76fd782ce684
Signed-off-by: Joel King <joelking@codeaurora.org>