diag: Generalize peripherals and channel types

Macros referring to different peripherals have the type of channel
in their name and the macros for channel types have the underlying
transport in their name. This patch renames the macros used in
Diag driver.

Change-Id: I0c98e7e4fde68716bf3491e143603618d1740dac
Signed-off-by: Ravi Aravamudhan <aravamud@codeaurora.org>