scripts/setup.sh: avoid clobbering $bdf variable

The get_nvme_name_from_bdf function uses the variable name $bdf, which
is also used as a loop iterator in its caller; since variables are
global by default in bash, this overwrites the original $bdf and may
cause unexpected behavior like skipping setup of some NVMe devices.

The long-term fix should be to declare all variables local in all
functions, but a minimal, targeted fix is to just rename the variable in
the inner function.

Change-Id: I53a877606a585415e8af525c6162ed7b0f67ba45
Signed-off-by: Daniel Verkamp <daniel.verkamp@intel.com>
Reviewed-on: https://review.gerrithub.io/403370


Tested-by: SPDK Automated Test System <sys_sgsw@intel.com>
Reviewed-by: Shuhei Matsumoto <shuhei.matsumoto.xt@hitachi.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>