spi: omap2-mcspi: Fix modifying platform resource data

currently during probe the resource data gets modified and device
physical address remains valid only during first load. If the module is
unloaded and loaded again, the ioremp will be done on a incorrect address
as the resource was modified during previous module load.
This patch fixes this issue.

Signed-off-by: Vikram N <vicky773@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>