libnl: fix two parentheses bugs in lib/cache_mngr.c file

libnl: fix two parentheses bugs in lib/cache_mngr.c file

there are two parentheses bugs in libnl /lib/cache_mngr.c file.
The parentheses doesn't make any sense,
This will cause the variable err get a bool value,
the correct value of variable err should be the return value
of the function which can be any integer value.

(From OE-Core rev: b8bf6cc43dd08fcc7394053b31f03d5312ed239c)

Signed-off-by: Song Li <Song.Li@windriver.com>
Signed-off-by: Mark Hatle <mark.hatle@windriver.com>
Signed-off-by: Saul Wold <sgw@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>