uwb: fix compiler warning on i1480_est_id_table

Annotate i1480_est_id_table as '__used' to fix following warning:

  CC      drivers/uwb/i1480/i1480-est.o
drivers/uwb/i1480/i1480-est.c:94: warning: ‘i1480_est_id_table’ defined but not used

Signed-off-by: Namhyung Kim <namhyung@gmail.com>
Cc: David Vrabel <david.vrabel@csr.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>