Platform/ARM: replace hardcoded VenHW() device paths referring to NOR flash

The ArmPlatformPkg NOR flash driver has been updated to use device paths
consisting of a fixed GUID and a numeric index rather than a separate GUID
for each flash bank on a given system. This means all explicit device path
references to NOR flash banks have to be brought up to date as well.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org>
Tested-by: Thomas Abraham <thomas.abraham@arm.com>