kernel: prevent cryptomgr from pulling in useless extra dependencies for tests that are not run

Reduces kernel size after LZMA by about 5k on MIPS

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@35325 3c298f89-4303-0410-b956-a3cf2f4a3e73
ar71xx: disable support for unsupported mtd configuration, saves about 5K kernel size after lzma

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@35326 3c298f89-4303-0410-b956-a3cf2f4a3e73