Drop redundant devel requirements

It is first time I see that "-devel" package requires packages which are
needed for build only. Also the "libusb1-devel" dependency seems to be
outdated. Let's remove those "Requires:" statements completely.

libmtp.spec

@@ -3,7 +3,7 @@
 
 Name:           libmtp
 Version:        1.1.18
-Release:        2%{?dist}
+Release:        3%{?dist}
 Summary:        Software library for MTP media players
 URL:            http://libmtp.sourceforge.net/
 
@@ -35,9 +35,6 @@ devices.
 %package devel
 Summary:        Development files for libmtp
 Requires:       %{name}%{?_isa} = %{version}-%{release}
-Requires:       pkgconfig
-Requires:       libusb1-devel
-Requires:       libgcrypt-devel
 
 %description devel
 This package provides development files for the libmtp
@@ -107,6 +104,9 @@ chrpath --delete $RPM_BUILD_ROOT{%{_bindir},/usr/lib/udev}/mtp*
 %{_libdir}/pkgconfig/libmtp.pc
 
 %changelog
+* Wed May 26 2021 Ondrej Holy <oholy@redhat.com> - 1.1.18-3
+- Drop redundant devel requires
+
 * Tue Jan 26 2021 Fedora Release Engineering <releng@fedoraproject.org> - 1.1.18-2
 - Rebuilt for https://fedoraproject.org/wiki/Fedora_34_Mass_Rebuild