Revert "generic: busybox: enable sha512sum to workaround segfault issue"

This reverts commit dcff68029e40ffa5bea3f3c83031862e7d72222d.

targets/generic

@@ -4,7 +4,6 @@ config 'CONFIG_ALL_NONSHARED=y'
 
 config 'CONFIG_BUSYBOX_CUSTOM=y'
 config 'CONFIG_BUSYBOX_CONFIG_SHA256SUM=y'
-config 'CONFIG_BUSYBOX_CONFIG_SHA512SUM=y'
 config '# CONFIG_BUSYBOX_CONFIG_FEATURE_PREFER_IPV4_ADDRESS is not set'
 
 config '# CONFIG_KMOD_BATMAN_ADV_MCAST is not set'