wifi: Modify the default value of SIMNum to 0 instead of 1.

sim_num value in conf file has to be updated only if it has
non zero value.In order to check this,the default value of
SIMNum is modified to 0 instead of 1, otherwise the existing
sim_num value is overwritten with the default value which
in turn makes the supplicant to always authenticate with
the default sim_num 1.

Change-Id: I47d0fb00c98c3cef37548ee595b3862ee6137e95
CRs-Fixed: 780903