lib: bitmap: add performance test for bitmap_print_to_pagebuf

Functional tests for bitmap_print_to_pagebuf() are provided
in lib/test_printf.c. This patch adds performance test for
a case of fully set bitmap.

Signed-off-by: Yury Norov <yury.norov@gmail.com>
Tested-by: Wolfram Sang <wsa+renesas@sang-engineering.com>