jedec_flash: Only use manufacturer defines from common flash.h

This patch removes the double defined manufacturer defines from
jedec_flash.c. Since the common defines in flash.h are 32bit
we now need the (16) cast. This patch also removes the compilation
warning (e.g. seen on hcu5):

./MAKEALL hcu5
Configuring for hcu5 board...
jedec_flash.c:219: warning: large integer implicitly truncated to unsigned type

Signed-off-by: Stefan Roese <sr@denx.de>