Xilinx QSPI Flash Patches

[aaron.nyholm at unfoldedeffective.com]

Hi All,

Attached are V2 of the patches that adds a wrapper around Xilinx's$
XQspiPsu flash driver to rtems_flashdev. This has been placed in$
bsp/shared. The JFFS2 driver has been removed as it is outdated.

Thanks,
Aaron.