kernel: remove already upstream applied patch

Remove 131-MIPS-export-get_c0_perfcount_int.patch which was already applied
in 4.1.6. This fixes the following build error:

arch/mips/ath79/setup.c:217:77: error: redefinition of '__kstrtab_get_c0_perfcount_int'
arch/mips/ath79/setup.c:211:77: note: previous definition of '__kstrtab_get_c0_perfcount_int' was here
arch/mips/ath79/setup.c:217:350: error: redefinition of '__ksymtab_get_c0_perfcount_int'
arch/mips/ath79/setup.c:211:350: note: previous definition of '__ksymtab_get_c0_perfcount_int' was here
scripts/Makefile.build:258: recipe for target 'arch/mips/ath79/setup.o' failed

Reported-by: swalker
Signed-off-by: Jonas Gorski <jogo@openwrt.org>

SVN-Revision: 46715