The local variable err in several functions in the fm10k_netdev.c file
is initialized with a value that is never used. The err value is
immediately re-assigned in all cases where it will be checked. Remove
the unnecessary initializers.

This was detected by cppcheck and resolves the following warnings
produced by that tool:

[fm10k_netdev.c:999] -> [fm10k_netdev.c:1004]: (style) Variable 'err' is
reassigned a value before the old one has been used.

[fm10k_netdev.c:1019] -> [fm10k_netdev.c:1024]: (style) Variable 'err'
is reassigned a value before the old one has been used.

[fm10k_netdev.c:64]: (style) Variable 'err' is assigned a value that is
never used.

[fm10k_netdev.c:131]: (style) Variable 'err' is assigned a value that
is never used.
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>