sysmobts: Fix compiler warning by including utils.h
sysmobts: Fix compiler warning by including utils.h

calib_file.c: In function 'next_calib_file_idx':
calib_file.c:126:3: warning: implicit declaration of function 'band_femto2osmo' [-Wimplicit-function-declaration]

geosphere/osmo-bts,osmocom/osmo-bts,telenoobie/osmo-bts,geosphere/osmo-bts,geosphere/osmo-bts,telenoobie/osmo-bts,geosphere/osmo-bts,telenoobie/osmo-bts,osmocom/osmo-bts,osmocom/osmo-bts,telenoobie/osmo-bts