Pb1200/DBAu1200: fix bad IDE resource size

The header files for the Pb1200/DBAu1200 boards have wrong definition for the
IDE interface's decoded range length -- it should be 512 bytes according to
what the IDE driver does.  In addition, the IDE platform device claims 1 byte
too many for its memory resource -- fix the platform code and the IDE driver
in accordance.

Signed-off-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>