CFI: Small cleanup for FLASH_SHOW_PROGRESS

With this patch we don't need that many #ifdef's in the code. It moves
the subtraction into the macro and defines a NOP-macro when
CONFIG_FLASH_SHOW_PROGRESS is not defined.

Signed-off-by: Stefan Roese <sr@denx.de>
Acked-by: Gerald Van Baren <vanbaren@cideas.com>