SPI: Fix and enable Fast Read support

- Fix handling of 5-byte Fast Read command in the ICH SPI
driver.  This fix is ported from the U-boot driver.
- Allow CONFIG_SPI_FLASH_NO_FAST_READ to be overridden by
defining a name for the bool in Kconfig and removing the
forced select in southbridge config
- Fix use of CONFIG_SPI_FLASH_NO_FAST_READ in SPI drivers
to use #if instead of #ifdef
- Relocate flash functions in SMM so they are usable.
This really only needs to happen for read function pointer
since it uses a global function rather than a static one from
the chip, but it is good to ensure the rest are set up
correctly as well.

Change-Id: Ic1bb0764cb111f96dd8a389d83b39fe8f5e72fbd
Signed-off-by: Duncan Laurie <dlaurie@chromium.org>
Reviewed-on: http://review.coreboot.org/1775
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>

src/include/spi.h

@@ -46,6 +46,7 @@
 
 /* SPI opcodes */
 #define SPI_OPCODE_WREN 0x06
+#define SPI_OPCODE_FAST_READ 0x0b
 
 /*-----------------------------------------------------------------------
  * Representation of a SPI slave, i.e. what we're communicating with.