locks: linker variables to calculate per-cpu bakery lock size

This patch introduces explicit linker variables to mark the start and
end of the per-cpu bakery lock section to help bakery_lock_normal.c
calculate the size of the section. This patch removes the previously
used '__PERCPU_BAKERY_LOCK_SIZE__' linker variable to make the code
uniform across GNU linker and ARM linker.

Change-Id: Ie0c51702cbc0fe8a2076005344a1fcebb48e7cca
Signed-off-by: Varun Wadekar <vwadekar@nvidia.com>