flash/nor: Factor out CFI memory read/write functions
Create separate memory read/write functions which facilitate access
to the CFI NOR, so that they can be replaced by controller-specific
functions if necessary. This would become necessary when implementing
support for e.g. HyperFlash controllers, which do not directly map
the HyperFlash into the address space.
Change-Id: I1bba1edfd397cb37bfedb43efe2dd03feb26a375
Signed-off-by: Marek Vasut <marek.vasut@gmail.com>
Reviewed-on: http://openocd.zylin.com/5145
Tested-by: jenkins
Reviewed-by: Paul Fertser <fercerpav@gmail.com>