Fix compilation error against Linux 3.7 kernel headers.

The for multistream checks were wrong and when dvblast was compiled
against kernel headers that contain multistream support the build
failed with:

  CC      dvb.c
  In file included from dvb.c:47:0:
  /usr/include/linux/dvb/frontend.h:65:2: error: expected identifier before numeric constant
  dvb.c: In function ‘FrontendInfo’:
  dvb.c:776:5: error: ‘FE_CAN_2G_MODULATION’ undeclared (first use in this function)
  dvb.c:776:5: note: each undeclared identifier is reported only once for each function it appears in
  dvb.c:779:5: error: ‘FE_NEEDS_BENDING’ undeclared (first use in this function)
  dvb.c:780:5: error: ‘FE_CAN_RECOVER’ undeclared (first use in this function)
  dvb.c:781:5: error: ‘FE_CAN_MUTE_TS’ undeclared (first use in this function)
  dvb.c: In function ‘FrontendSet’:
  dvb.c:1028:30: error: ‘FE_CAN_2G_MODULATION’ undeclared (first use in this function)
  make: *** [dvb.o] Error 1