HACK: scripts: headers_install: fix allmodconfig builds

Fix allmodconfig builds by adding exceptions for net_switch_config.h
warning: include/uapi/linux/net_switch_config.h: leak CONFIG_SWITCH_INVALID to user-space
warning: include/uapi/linux/net_switch_config.h: leak CONFIG_SWITCH_ADD_MULTICAST to user-space
warning: include/uapi/linux/net_switch_config.h: leak CONFIG_SWITCH_DEL_MULTICAST to user-space
warning: include/uapi/linux/net_switch_config.h: leak CONFIG_SWITCH_ADD_VLAN to user-space
...

Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>