package/rust: drop reference to HOST_RUST_JEMALLOC_CONF

This variable is no longer used since
4e3be3ae9d4c9f1b0c035eee0c923a724f9a9316 ("package/rust: bump version
to 1.33.0")

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/rust/rust.mk

@@ -65,7 +65,6 @@ define HOST_RUST_CONFIGURE_CMDS
 		echo 'channel = "stable"'; \
 		echo '[target.$(RUSTC_TARGET_NAME)]'; \
 		echo 'cc = "$(TARGET_CROSS)gcc"'; \
-		echo $(HOST_RUST_JEMALLOC_CONF); \
 	) > $(@D)/config.toml
 endef