tinymembench: Fix typo error on dependence

It should be BR2_MIPS_NABI64 instead of BR_MIPS_NABI64

Fixes:

   http://autobuild.buildroot.net/results/c5d/c5da2d99c09b1a2f7da23f1636f1ccc8978cc4a3/



Signed-off-by: Vicente Olivert Riera <Vincent.Riera@imgtec.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>