tty: hvc: hvc_vio: Staticify function invoked only by reference

mainline inclusion
from mainline-v5.11-rc1
commit 109af2a8
category: bugfix
bugzilla: 187303, https://gitee.com/openeuler/kernel/issues/I5ZXUG
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=109af2a82a36e0cedb54988406e6b40de67272c7



-------------------------------

Fixes the following W=1 kernel build warning(s):

 drivers/tty/hvc/hvc_vio.c:181:6: warning: no previous prototype for ‘hvterm_hvsi_hangup’ [-Wmissing-prototypes]
 181 | void hvterm_hvsi_hangup(struct hvc_struct *hp, int data)
 | ^~~~~~~~~~~~~~~~~~

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jirislaby@kernel.org>
Cc: linuxppc-dev@lists.ozlabs.org
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Link: https://lore.kernel.org/r/20201104193549.4026187-33-lee.jones@linaro.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Cai Xinchen <caixinchen1@huawei.com>
Reviewed-by: GONG Ruiqi <gongruiqi1@huawei.com>
Reviewed-by: Wang Weiyang <wangweiyang2@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>