pkg-config: Remove non-generated field

These fields are only replaced for packages using AX_PKG_CHECK_MODULES
diff --git a/src/gpioplus.pc.in b/src/gpioplus.pc.in
index 7df42e8..e9d3536 100644
--- a/src/gpioplus.pc.in
+++ b/src/gpioplus.pc.in
@@ -6,7 +6,5 @@
 Name: gpioplus
 Description: C++ wrapper around the Linux userspace GPIO API
 Version: @VERSION@
-Requires: @AX_PACKAGE_REQUIRES@
-Requires.private: @AX_PACKAGE_REQUIRES_PRIVATE@
 Cflags: -I${includedir}
 Libs: -L${libdir} -lgpioplus