ARM: pxa/tosa: drop setting LED trigger name, as it's unsupported now

Since 2e48928d8a0f38c1b5c81eb3f1294de8a6382c68 it's no longer possible to set
the name of the LED trigger for RFKILL events. Drop respective code from tosa-bt.c

Signed-off-by: Dmitry Eremin-Solenikov <dbaryshkov@gmail.com>
Cc: Stephen Hemminger <shemminger@vyatta.com>
Cc: John W. Linville <linville@tuxdriver.com>
Signed-off-by: Eric Miao <eric.y.miao@gmail.com>