adi_v5: Rename AP_REG_* to MEM_AP_REG_* and add LA support

adi_v5: Rename AP_REG_* to MEM_AP_REG_* and add LA support

This is a TODO in the src/target/arm_adi_v5.h for MEM-AP registers.

Some new registers are introduced in ADIv5.2 specification.
  MEM_AP_REG_MGT    (0x20) // Memory Barrier Transfer register
  MEM_AP_REG_TAR64  (0x08) // Bits[63:32] of Transfer Address
  MEM_AP_REG_BASE64 (0xF0) // Bits[63:32] of Debug Base Address

Refer to
  7.5 MEM-AP register summary in
  IHI0031C: ARM Debug Interface Architecture Specification ADIv5.0 to ADIv5.2

Change-Id: I3bc4296a04c35f5c64f851e5865d3099922613fa
Signed-off-by: Alamy Liu <alamy.liu@gmail.com>
Reviewed-on: http://openocd.zylin.com/2904
Tested-by: jenkins
Reviewed-by: Matthias Welwarsky <matthias@welwarsky.de>
Reviewed-by: Andreas Fritiofson <andreas.fritiofson@gmail.com>