In "struct lpc32xx_kscan_drv", the 'irq' field is unused.
Remove it.

Found with cppcheck, unusedStructMember.

While at it, move the 'row_shift' field in order to fill a hole in the
structure (at least on 64 bits arch).
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Link: https://lore.kernel.org/r/e006dfb77e35762c6e4f8ba6ba792b0c52fde375.1714545542.git.christophe.jaillet@wanadoo.frSigned-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>