configure: fix up inconsistent indentation

Whitespace modifications only, no functional change.

Change-Id: I984bd4299a7a49d116bee6f723f71e094ecd2209
Signed-off-by: Daniel Verkamp <daniel.verkamp@intel.com>
Reviewed-on: https://review.gerrithub.io/369483


Tested-by: SPDK Automated Test System <sys_sgsw@intel.com>
Reviewed-by: Ben Walker <benjamin.walker@intel.com>