isdn: add missing MODULE_DESCRIPTION() macros

isdn: add missing MODULE_DESCRIPTION() macros

make allmodconfig && make W=1 C=1 reports:
WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/isdn/hardware/mISDN/hfcpci.o
WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/isdn/hardware/mISDN/hfcmulti.o
WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/isdn/hardware/mISDN/hfcsusb.o
WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/isdn/hardware/mISDN/avmfritz.o
WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/isdn/hardware/mISDN/speedfax.o
WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/isdn/hardware/mISDN/mISDNinfineon.o
WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/isdn/hardware/mISDN/w6692.o
WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/isdn/hardware/mISDN/netjet.o
WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/isdn/hardware/mISDN/mISDNipac.o
WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/isdn/hardware/mISDN/mISDNisar.o
WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/isdn/mISDN/mISDN_core.o
WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/isdn/mISDN/mISDN_dsp.o
WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/isdn/mISDN/l1oip.o

Add the missing invocations of the MODULE_DESCRIPTION() macro.

Signed-off-by: Jeff Johnson <quic_jjohnson@quicinc.com>
Link: https://lore.kernel.org/r/20240607-md-drivers-isdn-v1-1-81fb7001bc3a@quicinc.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>