remove some unused symbols, maybe we need kernel version specific global file

target/linux/kernel.config

@@ -1,5 +1,4 @@
 CONFIG_DEFAULT_HOSTNAME="openadk"
-CONFIG_CMDLINE_BOOL=y
 CONFIG_CMDLINE=""
 CONFIG_SYSVIPC=y
 CONFIG_SYSVIPC_SYSCTL=y
@@ -15,7 +14,6 @@ CONFIG_EMBEDDED=y
 CONFIG_MODULES=y
 CONFIG_BINFMT_ELF=y
 CONFIG_BINFMT_SCRIPT=y
-CONFIG_HOTPLUG=y
 CONFIG_STANDALONE=y
 CONFIG_FUTEX=y
 CONFIG_EPOLL=y