sys_log: replace old debug macros at USB stack

USB stack is now using new system log macros, updated the Kconfig
variable to be a level rather than a bool and the .conf files at
samples.

JIRA: ZEP-311

Change-Id: I873ee0f12b81a364307cdac27a2e058a43d4c9ea
Signed-off-by: Genaro Saucedo Tejada <genaro.saucedo.tejada@intel.com>
4 files changed