Revert "Flip IOP: modify_roi_in(): drop sanity check"

This reverts commit 3484731e3295f619bb99d41b3a12ba39e5c78919.
Flip IOP: modify_roi_in(): sanity check: do not use iwidth/iheight but buf_in.width/buf_in.height

iwidth/iheight is the size of original input buffer, which is correct
only if there is nothing in between changing the roi (like scalepixels, flip)
Clipping IOP: modify_roi_in(): sanity check: do not use iwidth/iheight but buf_in.width/buf_in.height

iwidth/iheight is the size of original input buffer, which is correct
only if there is nothing in between changing the roi (like scalepixels, flip)
Lens IOP: do not use iwidth/iheight but buf_in.width/buf_in.height

iwidth/iheight is the size of original input buffer, which is correct
only if there is nothing in between changing the roi (like scalepixels)
Clipping IOP: modify_roi_in(): sanity check: fix int inaccuracies
Cleanup: drop unused iflipped from dt_dev_pixelpipe_t
Merge pull request #717 from LebedevRI/modify_roi_in-fix

Fix iwidht vs. buf_in.widht issues