[NEUS7920-133][9610] wlbt: Add observer information in sbl header

[NEUS7920-133][9610] wlbt: Add observer information in sbl header

Sable user should be notified of the presence of one or more observers
when the trigger collection occurs. This will help to indicate that the
mxlog and udi chunks might be out of date.

The presence of observer[s] is included in a new field of the sable
header.

To indicate to the decoder the new header structure, it has been decided
to increase the sbl version from 2.0 to 2.1

Change-Id: I6b87ab2f950300482d2025a0c79914c5d24751b8
SCSC-Bug-Id: SSB-50521
Signed-off-by: Albert Cano <a.canocamps@samsung.com>