riscv-pk: make it machine-specific

bbl has a machine specific payload (vmlinux), so it should be
machine-specific too. Otherwise riscv-pk build for different machines
will collide.

Signed-off-by: Taras Kondratiuk <takondra@cisco.com>

recipes-devtools/riscv-tools/riscv-pk.bb

@@ -9,6 +9,8 @@ SRC_URI = "git://github.com/riscv/riscv-pk.git \
            file://0001-add-acinclude.m4.patch \
           "
 
+PACKAGE_ARCH = "${MACHINE_ARCH}"
+
 LDFLAGS_append = " -Wl,--build-id=none"
 
 inherit autotools