bl31: add new bl31 with extended spi support

Updated BL31 to include support for extended SPI. Update build
instructions for building from source. Binary was built from upstream
trusted-firmware-a commit:
6a5022278b0bda10708534ef5cc6c1b5256081ee
Merge: 53be5274f 14a6fed5a

Signed-off-by: Raghu Krishnamurthy <raghu.ncstate@gmail.com>
Change-Id: Ia025d976e50d4c05d7e63cd8cdb4f404ac300c9e
2 files changed
tree: 775a3b5f67da3488338086bb0f302469b361b87f
  1. darwin-x64/
  2. generic/
  3. linux-aarch64/
  4. linux-x64/