HSD #18019805663: mtd: spi-nor: issi: Add IS25WP512 device

commit b54afecbad98ecec0cb0c18f27cbff73c867a66f from
https://github.com/altera-opensource/linux-socfpga.git



Add is25wp512 info to spi_nor_ids[] table entry.

Rename is25lp256_post_bfpt_fixups to is_post_bfpt_fixups as a
common function for all is25xx post_bfpt fixups.

Signed-off-by: Niravkumar L Rabara <niravkumar.l.rabara@intel.com>
Signed-off-by: Wenlin Kang <wenlin.kang@windriver.com>
Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com>