Bluetooth: bpa10x: make array 'req' static, shrinks object size

Don't populate the const read-only array 'req' on the stack but instead
make it static. Makes the object code smaller by over 40 bytes:

Before:
   text	   data	    bss	    dec	    hex	filename
   8497	   3408	    128	  12033	   2f01	linux/drivers/bluetooth/bpa10x.o

After:
   text	   data	    bss	    dec	    hex	filename
   8366	   3496	    128	  11990	   2ed6	linux/drivers/bluetooth/bpa10x.o

(gcc version 7.2.0 x86_64)

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>