librtlsdr: fix typo in LIBRTLSDR_CONF_OPTS variable name

Commit 9ff035839eef68eb16e90ae70c3e70dc7f57ca5e ("librtlsdr: fix
static build") introduced this obvious typo, which was spotted by
check-package:

package/librtlsdr/librtlsdr.mk:18: possible typo: LIBRTLSDRCONF_OPTS -> *LIBRTLSDR*

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

package/librtlsdr/librtlsdr.mk

@@ -15,7 +15,7 @@ LIBRTLSDR_DEPENDENCIES = libusb
 ifeq ($(BR2_STATIC_LIBS),y)
 LIBRTLSDR_CONF_OPTS += -DBUILD_STATIC_LIBS=ON
 else ifeq ($(BR2_SHARED_STATIC_LIBS),y)
-LIBRTLSDRCONF_OPTS += -DBUILD_STATIC_LIBS=ON
+LIBRTLSDR_CONF_OPTS += -DBUILD_STATIC_LIBS=ON
 else ifeq ($(BR2_SHARED_LIBS),y)
 LIBRTLSDR_CONF_OPTS += -DBUILD_STATIC_LIBS=OFF
 endif