cmd: bdinfo: Enable dumping lmb data when LMB is enabled

The commit 9996cea7 ("lmb/bdinfo: dump lmb info via bdinfo") added
support for dumping LMB information as the part of bdinfo. But code itself
should be called only when LMB is enabled.

Signed-off-by: Michal Simek <michal.simek@amd.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Link: https://lore.kernel.org/r/3e40c8bb77550dfca9f7eb48fe644a018d971411.1662537127.git.michal.simek@amd.com