package/pppd: drop PPPD_DROP_INTERNAL_IF_PPOL2TP_H

PPPD_DROP_INTERNAL_IF_PPOL2TP_H is not needed since bump to version
2.4.6 in commit 49b239ab20e632792a6c61173ba830cdc2128ebf and
https://github.com/ppp-project/ppp/commit/c41092dd4c49267f232f6cba3d31c6c68bfdf68d

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>
(cherry picked from commit 0a0dd63c824c1c8a104e09b4f773764daf5b3e3f)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/pppd/pppd.mk

@@ -37,15 +37,6 @@ PPPD_DEPENDENCIES += libpcap
 PPPD_MAKE_OPTS += FILTER=y
 endif
 
-# pppd bundles some but not all of the needed kernel headers. The embedded
-# if_pppol2tp.h is unfortunately not compatible with kernel headers > 2.6.34,
-# and has been part of the kernel headers since 2.6.23, so drop it
-define PPPD_DROP_INTERNAL_IF_PPOL2TP_H
-	$(RM) $(@D)/include/linux/if_pppol2tp.h
-endef
-
-PPPD_POST_EXTRACT_HOOKS += PPPD_DROP_INTERNAL_IF_PPOL2TP_H
-
 # pppd defaults to /etc/ppp/resolv.conf, which not be writable and is
 # definitely not useful since the C library only uses
 # /etc/resolv.conf. Therefore, we change pppd to use /etc/resolv.conf