msm: mdss: skip panel type node change during resolution switch

The panel type sysfs node indicates the type of panel that
is currently in use, either video or cmd mode. This is
updated after every dynamic switch. Currently, this node
is updated to an invalid value during dynamic resolution switch.
Skip the setting as the mode is not changed during resolution
switch.

Change-Id: Ic002ad587eeade068561c0e9f1d29aeb1689ada5
Signed-off-by: Veera Sundaram Sankaran <veeras@codeaurora.org>