mkhex: Move it to tools/misc

It makes more sense to put a tool to be used by other subsystems
to be in 'tools/misc' along 'mkrpm','mkdeb', etc.

The patch titled "xen/livepatch/x86/arm32: Force .livepatch.depends
section to be uint32_t aligned" uses mkhex.

Acked-by: Wei Liu <wei.liu2@citrix.com>
Suggested-by: Julien Grall <julien.grall@arm.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

tools/firmware/hvmloader/Makefile

@@ -91,23 +91,23 @@ roms.inc: $(ROMS)
 
 ifneq ($(ROMBIOS_ROM),)
 	echo "#ifdef ROM_INCLUDE_ROMBIOS" >> $@.new
-	sh ./mkhex rombios $(ROMBIOS_ROM) >> $@.new
+	sh ../../misc/mkhex rombios $(ROMBIOS_ROM) >> $@.new
 	echo "#endif" >> $@.new
 endif
 
 ifneq ($(STDVGA_ROM),)
 	echo "#ifdef ROM_INCLUDE_VGABIOS" >> $@.new
-	sh ./mkhex vgabios_stdvga $(STDVGA_ROM) >> $@.new
+	sh ../../misc/mkhex vgabios_stdvga $(STDVGA_ROM) >> $@.new
 	echo "#endif" >> $@.new
 endif
 ifneq ($(CIRRUSVGA_ROM),)
 	echo "#ifdef ROM_INCLUDE_VGABIOS" >> $@.new
-	sh ./mkhex vgabios_cirrusvga $(CIRRUSVGA_ROM) >> $@.new
+	sh ../../misc/mkhex vgabios_cirrusvga $(CIRRUSVGA_ROM) >> $@.new
 	echo "#endif" >> $@.new
 endif
 ifneq ($(ETHERBOOT_ROMS),)
 	echo "#ifdef ROM_INCLUDE_ETHERBOOT" >> $@.new
-	sh ./mkhex etherboot $(ETHERBOOT_ROMS) >> $@.new
+	sh ../../misc/mkhex etherboot $(ETHERBOOT_ROMS) >> $@.new
 	echo "#endif" >> $@.new
 endif