MFC r316080,r316081,r316115:

r316080:

Fix some localized style(9) issues and reword CAM_ERRBUF_SIZE description

The CAM_ERRBUF_SIZE description rewording fixes a typo by proxy.

r316081:

Use sizeof(cam_errbuf) instead of CAM_ERRBUF_SIZE in snprintf calls

Reindent snprintf calls' arguments to match style(9) guidelines with
respect to indentation.

r316115:

libcam: use func instead of hardcoding the function name as func_name

Tested with: cam_device_copy(NULL, NULL) // ;)..