tty: hvc: make symbol 'hvc_udbg_dev' static

mainline inclusion
from mainline-v5.13-rc1
commit 63bbdb4e
category: bugfix
bugzilla: 187303, https://gitee.com/openeuler/kernel/issues/I5ZXTT
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=63bbdb4ea02b17f929fa4f5c536357183eba9639



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

The sparse tool complains as follows:

drivers/tty/hvc/hvc_udbg.c:20:19: warning:
 symbol 'hvc_udbg_dev' was not declared. Should it be static?

This symbol is not used outside of hvc_udbg.c, so this
commit marks it static.

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Link: https://lore.kernel.org/r/20210407125826.4139130-1-yukuai3@huawei.com


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>
Reviewed-by: Xiu Jianfeng <xiujianfeng@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>