tools: hv: Fix cross-compilation

Use the native ARCH only in case it is not set, this will allow the
cross-compilation where ARCH is explicitly set.

Additionally, simplify the ARCH check to build the fcopy daemon only
for x86 and x86_64.

Fixes: 82b0945 ("tools: hv: Add new fcopy application based on uio driver")
Reported-by: Adrian Vladu <avladu@cloudbasesolutions.com>
Closes: https://lore.kernel.org/linux-hyperv/PR3PR09MB54119DB2FD76977C62D8DD6AB04D2@PR3PR09MB5411.eurprd09.prod.outlook.com/
Co-developed-by: Saurabh Sengar <ssengar@linux.microsoft.com>
Signed-off-by: Saurabh Sengar <ssengar@linux.microsoft.com>
Signed-off-by: Aditya Garg <gargaditya@linux.microsoft.com>
Reviewed-by: Roman Kisel <romank@linux.microsoft.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>

Author: Aditya Garg

tools/hv/Makefile

@@ -2,7 +2,7 @@
 # Makefile for Hyper-V tools
 include ../scripts/Makefile.include
 
-ARCH := $(shell uname -m 2>/dev/null)
+ARCH ?= $(shell uname -m 2>/dev/null)
 sbindir ?= /usr/sbin
 libexecdir ?= /usr/libexec
 sharedstatedir ?= /var/lib
@@ -20,7 +20,7 @@ override CFLAGS += -O2 -Wall -g -D_GNU_SOURCE -I$(OUTPUT)include
 override CFLAGS += -Wno-address-of-packed-member
 
 ALL_TARGETS := hv_kvp_daemon hv_vss_daemon
-ifneq ($(ARCH), aarch64)
+ifneq ($(filter x86_64 x86,$(ARCH)),)
 ALL_TARGETS += hv_fcopy_uio_daemon
 endif
 ALL_PROGRAMS := $(patsubst %,$(OUTPUT)%,$(ALL_TARGETS))