The changes included to  access spi-flash are:
1] Add condition to check if SPI-FLASH is enabled in core or not.
2] Enable big_endian field for spi flash platform data to be identified on vme
3] Define frequencies using macro to maintain consistency throughout the code
4] Add correct flash chip/part number
Signed-off-by: Mamta Shukla <mamta.ramendra.shukla@cern.ch>