msm: mdss: fix dsi hw config string parsing

The dsi hw config is parsed from the string passed from bootloader.
It is parsed based on the delimiter ':', but when a panel is booted
in simulator mode, an additional override parameter prefixed with '#'
is passed from bootloader. Fix the parsing to account for the override
parameter when simulator panels are used.

Change-Id: Id9d7419179048d8b564efbbb8ea238d987d6a83c
Signed-off-by: Veera Sundaram Sankaran <veeras@codeaurora.org>