dm-latency: change latency stats levels and finess

Previous 20 levels was not enough, and max measurable was 190ms. It was
not enough to gether more accurate latency stats information.

This commit change levels to 20, and max measurable latency to 490ms.
dm-latency: several bug fixes to lib_dm_io_latency.c

Fixes several bugs in lib_dm_io_latency.c including,
1, in check_parameters() uses strdup() to copy a string, then call basename(), because basename() may change target_name parameter.
2, fix a return value typo in load_system_default_configs()
3, modify printf debug information, only call printf when DEBUG is defined.
4, in is_dm_target_io_latency_ok(), if there are errors, returns -1.
dm-latency: demo program to use lib_dm_io_latency

Add a demo program latency_warning.c to show how to use lib_dm_io_latency library.
dm-latency: remove 0001-dm-and-trace-info.patch

Patch 0001-dm-and-trace-info.patch only adds printk information, in
2.6.32 kernel this patch is useless, remove it.