libata: zpodd: make arrays cdb static, reduces object code size

Don't populate the arrays cdb on the stack, instead make them static.
Makes the object code smaller by 230 bytes:

Before:
   text	   data	    bss	    dec	    hex	filename
   3797	    240	      0	   4037	    fc5	drivers/ata/libata-zpodd.o

After:
   text	   data	    bss	    dec	    hex	filename
   3407	    400	      0	   3807	    edf	drivers/ata/libata-zpodd.o

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Tejun Heo <tj@kernel.org>