build: use pkg_check_modules instead of ax_pkg_check_modules

ax_pkg_check_modules provides a wrapper to pkg_check_modules, such that
one can specify private and public dependencies.  This is not used,
therefore use the underlying macro.

Change-Id: I556f9e29da236e069b7a9b69448fb4cbcba7bbe1
Signed-off-by: Patrick Venture <venture@google.com>

configure.ac

@@ -53,7 +53,7 @@ AS_IF([test "x$enable_virtual_pnor" == "xyes"],
     [
         PKG_CHECK_MODULES([SDBUSPLUS], [sdbusplus])
         PKG_CHECK_MODULES([PHOSPHOR_LOGGING], [phosphor-logging])
-        AX_PKG_CHECK_MODULES([PHOSPHOR_DBUS_INTERFACES], [],[phosphor-dbus-interfaces])
+        PKG_CHECK_MODULES([PHOSPHOR_DBUS_INTERFACES], [phosphor-dbus-interfaces])
 
         AM_CONDITIONAL(VIRTUAL_PNOR_ENABLED, true)
         AX_APPEND_COMPILE_FLAGS([-DVIRTUAL_PNOR_ENABLED], [CXXFLAGS])