linux: unbreak host tools build for 4.14

Remove a stray -Wp left in host_c_flags causing build failures for newer
4.14 versions.

Reported-by: Michael Marley <michael@michaelmarley.com>
Signed-off-by: Jonas Gorski <jonas.gorski@gmail.com>

target/linux/generic/hack-4.14/211-host_tools_portability.patch

@@ -17,7 +17,7 @@ Signed-off-by: Felix Fietkau <nbd@nbd.name>
  ## HOSTCC C flags
  
 -host_c_flags = -Wp,-MD,$(depfile) -Wp,-MT,$@ $(CHOSTFLAGS) -D"BUILD_STR(s)=\#s" $(CHOSTFLAGS_$(basetarget).o) $(CHOSTFLAGS_$(obj))
-+host_c_flags = -MD -MF $(depfile) -Wp -MT $@ $(CHOSTFLAGS) -D"BUILD_STR(s)=\#s" $(CHOSTFLAGS_$(basetarget).o) $(CHOSTFLAGS_$(obj))
++host_c_flags = -MD -MF $(depfile) -MT $@ $(CHOSTFLAGS) -D"BUILD_STR(s)=\#s" $(CHOSTFLAGS_$(basetarget).o) $(CHOSTFLAGS_$(obj))
 --- a/tools/perf/pmu-events/jevents.c
 +++ b/tools/perf/pmu-events/jevents.c
 @@ -35,6 +35,7 @@