make: Make V= flag parsing more clear
make: Make V= flag parsing more clear

No functional change.

The "else ifeq(x,y)" syntax is documented on the following page:
www.gnu.org/software/make/manual/html_node/Conditional-Syntax.html

The original change that brought in V=0:
crrev.com/c/427363

BRANCH=none
BUG=none
TEST=# Run before and after change to confirm output is the same
     make hosttests V=0
     make hosttests V=
     make hosttests V=1
     make hosttests V=kabob

Change-Id: I22021a794cc2e8dede845c0276a2cee67fa32550
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/2597809
Tested-by: Craig Hesling <383db090fd8ef907a606ac8a9eccd2962bc489cf@chromium.org>
Commit-Queue: Denis Brockus <6b21e8190fb5e373363fb95271367073a16474ef@chromium.org>
Reviewed-by: Denis Brockus <6b21e8190fb5e373363fb95271367073a16474ef@chromium.org>
Auto-Submit: Craig Hesling <383db090fd8ef907a606ac8a9eccd2962bc489cf@chromium.org>

coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec