powerpc/e6500: remove the stale TCD_LOCK macro

Since we moved the "lock" to be the first element of
struct tlb_core_data in commit 82d86de2 ("powerpc/e6500: Make TLB
lock recursive"), this macro is not used by any code. Just delete it.

Signed-off-by: Kevin Hao <haokexin@gmail.com>
Signed-off-by: Scott Wood <scottwood@freescale.com>