msm: smd: Remove dead code

Remove the following dead functionality:

Package configuration (MSM_SMD_PKG3/MSM_SMD_PKG4)
	All supported targets are Package 4 based, making Package 3
	unsupported and any code depending on it.

MSM_N_WAY_SMD
	All supported targets are n-way SMD.  This config is always true.

MSM_N_WAY_SMSM
	All supported targets are n-way SMSM.  This config is always true.

Legacy loopback
	Legacy loopback is unsupported and unused.

Legacy initialization (static and platform data)
	All supported targets use DT based initialization.

SMD wait until readable/writable API
	Unsupported and always excluded with a "#if 0" compiler statement

Unused SMSM bit definitions

SMSM/SMD interrupt muxing
	Muxing SMSM and SMD interrupts on the same irq line is unsupported
	and unused.

Legacy modem reset
	Legacy modem reset is unsupported and replaced by Subsystem Restart.

DEM support
	DEM is unsupported and unused.

Legacy SMD channel types
	All SMD channels are explictly identified as streaming or packet
	mode.

Change-Id: I358f0d084d61c01731ad6006ea2e6e4f9e6915a9
Signed-off-by: Jeffrey Hugo <jhugo@codeaurora.org>