comms/uhd: Remove PORTDOCS macro

The PORTDOCS macro was duplicating the files already listed in
pkg-plist.

===>  Building package for uhd-4.6.0.0_1
pkg-static: duplicate file listing: /usr/local/share/doc/uhd/LICENSE, fatal (developer mode)
pkg-static: duplicate file listing: /usr/local/share/doc/uhd/README.md, fatal (developer mode)

Approved by:	portmgr (blanket)

comms/uhd/Makefile

@@ -61,8 +61,6 @@ DOXYGEN_CMAKE_ON=	-DENABLE_DOXYGEN:STRING="ON"
 DOXYGEN_CMAKE_OFF=	-DENABLE_DOXYGEN:STRING="OFF" \
 			-DENABLE_MANUAL:STRING="OFF"
 
-PORTDOCS=	*
-
 do-install:
 # install host component
 # hack the install prefix now