kernel/sysctl: fix: 'warning: 'kbuf' may be used uninitialized in this function'

Signed-off-by: Dennis Rassmann <showp1984@gmail.com>
kernel/sysctl: fix: 'warning: 'kbuf' may be used uninitialized in this function' #2

Signed-off-by: Dennis Rassmann <showp1984@gmail.com>
MAKEFILE: optimize -O3
DEFCONFIG: optimize -O3
Linaro -O3 fixes