kernel: re-enable MIPS VDSO

kernel upstream commit 9efcaa7c4afba5628f2650a76f69c798f47eeb18 to 4.14
itself a backport of 0f02cfbc3d9e413d450d8d0fd660077c23f67eff has
resolved the cache line issues that led to us disabling VDSO by default
on MIPS.

Remove our force disable patch:

pending-4.14/206-mips-disable-vdso.patch

Signed-off-by: Kevin Darbyshire-Bryant <ldir@darbyshire-bryant.me.uk>
Acked-by: Hauke Mehrtens <hauke@hauke-m.de>

target/linux/generic/pending-4.14/206-mips-disable-vdso.patch

@@ -1,23 +0,0 @@
-From: Felix Fietkau <nbd@nbd.name>
-Subject: kernel: disable MIPS VDSO by default until the cache issues have been resolved
-
-lede-commit: 1185e645a773c86aa88cf04d0e2911dc62eb43f5
-Signed-off-by: Felix Fietkau <nbd@nbd.name>
----
- arch/mips/vdso/Makefile | 4 ++--
- 1 file changed, 2 insertions(+), 2 deletions(-)
-
---- a/arch/mips/vdso/Makefile
-+++ b/arch/mips/vdso/Makefile
-@@ -30,9 +30,9 @@ aflags-vdso := $(ccflags-vdso) \
- ifndef CONFIG_CPU_MIPSR6
-   ifeq ($(call ld-ifversion, -lt, 225000000, y),y)
-     $(warning MIPS VDSO requires binutils >= 2.25)
--    obj-vdso-y := $(filter-out gettimeofday.o, $(obj-vdso-y))
--    ccflags-vdso += -DDISABLE_MIPS_VDSO
-   endif
-+  obj-vdso-y := $(filter-out gettimeofday.o, $(obj-vdso-y))
-+  ccflags-vdso += -DDISABLE_MIPS_VDSO
- endif
- 
- # VDSO linker flags.