Making the opcode list 'const' saves memory.
Some function arguments and local variables needed 'const', too.

Add also 'static' to two local functions.

Reviewed-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
Signed-off-by: Stefan Weil <sw@weilnetz.de>
[EI: Removed old prototypes to fix the build]
Signed-off-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>