kgdb: fix gcc-11 warnings harder

kgdb: fix gcc-11 warnings harder

40cc3a80bb42 ("kgdb: fix gcc-11 warning on indentation") tried to fix up
the gcc-11 complaints in this file by just reformatting the #defines.
That worked for gcc 11.1.0, but in gcc 11.1.1 as shipped by Fedora 34,
the warning came back for one of the #defines.

Fix this up again by putting { } around the if statement, now it is
quiet again.

Fixes: 40cc3a80bb42 ("kgdb: fix gcc-11 warning on indentation")
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Daniel Thompson <daniel.thompson@linaro.org>
Cc: Jason Wessel <jason.wessel@windriver.com>
Link: https://lore.kernel.org/r/20210520130839.51987-1-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>