Revert "msm: modem-8960: Check if the modem is alive after restarting it"

This reverts commit 21b95f87.

Commit 21b95f was meant to read the modem watchdog register
in order to determine if the modem booted up correctly after
a subsystem restart sequence. However, the modem watchdog
state is indeterminate even after the modem initializes it,
since the modem software disables the watchdog during
certain power collapse modes.

CRs-Fixed: 378114
Change-Id: Id4d59ea978b4b7a1a2df3bd5a6856f6b565cbdb8
Signed-off-by: Vikram Mulukutla <markivx@codeaurora.org>