lib/vsprintf: don't increment buf in bitmap_list_string

lib/vsprintf: don't increment buf in bitmap_list_string

Increment is confusing as the buf is overritten at the same line.

Link: https://lkml.kernel.org/r/20210817193735.269942-1-yury.norov@gmail.com
Fixes: b1c4af4d3d6b (vsprintf: rework bitmap_list_string) (next-20210817)
Signed-off-by: Yury Norov <yury.norov@gmail.com>
Suggested-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Wolfram Sang <wsa+renesas@sang-engineering.com>
Cc: Alexander Lobakin <alobakin@pm.me>
Cc: Alexey Klimov <aklimov@redhat.com>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Ulf Hansson <ulf.hansson@linaro.org>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>