generic_board: Call "checkboard" even though the root node has a "model" property

generic_board: Call "checkboard" even though the root node has a "model" property

In case of enable CONFIG_OF_CONTROL and has a "model" property in the root node,
the board special "checkboard" will not be called.
Usually we show some useful version information in the function.
This patch enable call "checkboard" in any case.
It is not conflicting with showing "model" at the same time.

For example on LS2085AQDS:
Showing "model" only:
Model: Freescale Layerscape 2085a QDS Board

Showing "checkboard" only:
Board: LS2085E-QDS, Board Arch: V1, Board version: B, boot from vBank: 4

Showing both:
Model: Freescale Layerscape 2085a QDS Board
Board: LS2085E-QDS, Board Arch: V1, Board version: B, boot from vBank: 4

Signed-off-by: Haikun Wang <haikun.wang@freescale.com>
Reviewed-by: Simon Glass <sjg@chromium.org>