watchdog: alim7101_wdt: fix compiler warning on alim7101_pci_tbl

Annotate alim7101_pci_tbl as '__used' to fix following warning:

  CC      drivers/watchdog/alim7101_wdt.o
drivers/watchdog/alim7101_wdt.c:433: warning: ‘alim7101_pci_tbl’ defined but not used

Signed-off-by: Namhyung Kim <namhyung@gmail.com>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>