Pass seperate dev_t var to device_path_parse_major_minor

Pass seperate dev_t var to device_path_parse_major_minor

MIPS/O32's st_rdev member of struct stat is unsigned long, which
is 32bit, while dev_t is defined as 64bit, which make some problems
in device_path_parse_major_minor.

Don't pass st.st_rdev to device_path_parse_major_minor, while pass
a seperate var, and then assign into struct stat.

Gbp-Pq: Topic debian
Gbp-Pq: Name Pass-seperate-dev_t-var-to-device_path_parse_major_minor.patch