Win32: Fix 2 fullscreen bugs

First bug: I'm not sure why this was added(it was committed here: https://github.com/hrydgard/ppsspp/commit/b74b215f349e5e5bfcbd1baa27080a92b7a3b9e5) but it causes a bug when exiting fullscreen sometimes, so let's just remove it.

It appears to be the cause of this bug:
1. Start a game in windowed mode.
2. Enter fullscreen mode.
3. Reset game via CTRL + B(current reset shortcut)
4. Exit fullscreen via F11.
5. The window size is huge, like previous bugs.

Second bug: When entering fullscreen from 1x window size, mouse events wouldn't work. Adjustment of the factor variable not to apply to fullscreen mode fixes it. Fixes https://github.com/hrydgard/ppsspp/issues/3899.