Input: iqs5xx - expose firmware revision to user space

Input: iqs5xx - expose firmware revision to user space

Add the read-only 'fw_info' attribute which reports information
about the device's firmware in the following format:

a.b.c.d:e.f

Where:

a = Product number (e.g. 40 for IQS550)
b = Project number (e.g. 15)
c = Firmware revision (major)
d = Firmware revision (minor)
e = Customer-assigned exported file version (major)
f = Customer-assigned exported file version (minor)

As part of the corresponding rework to uses of 'bl_status', the
IQS5XX_BL_STATUS_RESET definition is dropped with 0 used in its
place instead.

Signed-off-by: Jeff LaBundy <jeff@labundy.com>
Link: https://lore.kernel.org/r/20210313191236.4366-4-jeff@labundy.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>