lmb: remove superfluous address overlap check from lmb_add_region_flags()

lmb: remove superfluous address overlap check from lmb_add_region_flags()

U-Boot allows re-use of already reserved memory through the
lmb_reserve() and lmb_alloc_addr() API's. This memory re-use is
allowed only when the flag of the existing reserved region and that of
the requested region is LMB_NONE. A check was put in the
lmb_add_region_flags() in commit 8b8b35a4f5e to handle the scenario
where an already reserved region was re-requested with region flag
other than LMB_NONE -- the function then returns -EEXIST in such a
scenario.

The lmb_reserve() function now does a check for a reservation request
with existing reserved regions, and returns -EEXIST in case of an
overlap but when the flag check fails. Remove this now redundant check
from lmb_add_region_flags().

Signed-off-by: Sughosh Ganu <sughosh.ganu@linaro.org>