Input: atmel-mxt_ts: Support firmware upgrade in bootloader mode

If a firmware upgrade fails, on subsequent boot retry a firmware
upgrade based on the bootloader id. This can be initiated through
the userspace program by writing into the update_fw sysfs entry.

Change-Id: I1d428c52f2cbfff8fe572a2bc6f0cd124111b810
Signed-off-by: Anirudh Ghayal <aghayal@codeaurora.org>