OpenOCD already defines the macro ARRAY_SIZE, while riscv code
uses a local macro DIM.
Prefer using the macro ARRAY_SIZE() instead of DIM().
Not all the riscv code has been upstreamed, yes; this patch only
covers the code not upstreamed.
Change-Id: Ie3e411280f76bc798f1d51c2574cfec148ee0d0d
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>