riscv: andes: Fix enable register settings of PLICSW

riscv: andes: Fix enable register settings of PLICSW

On 32-core platform, hart31 gets stuck at secondary_hart_loop
as the corresponding enable bit is not set in enable_ipi().
We should program the next word (0x2f84) which is assigned
as the enable register of hart31. It should be done in the same
way when we invoke riscv_send_ipi() to trigger software interrupt
on hart31.

The following diagram shows the enable bits of the fixed PLICSW
scheme.

   Pending regs: 0x1000  x---0---0---0---0------0---0
Pending hart ID:             0   1   2   3 ... 30  31
   Interrupt ID:         0   1   2   3   4 ... 31  32
                         |   |   |   |   |      |   |
    Enable regs: 0x2000  x---1---0---0---0-...--0---0---> hart0
                         |   |   |   |   |      |   |
                 0x2080  x---0---1---0---0-...--0---0---> hart1
                         |   |   |   |   |      |   |
                 0x2100  x---0---0---1---0-...--0---0---> hart2
                         |   |   |   |   |      |   |
                 0x2180  x---0---0---0---1-...--0---0---> hart3
                         .   .   .   .   .      .   .
                         .   .   .   .   .      .   .
                         .   .   .   .   .      .   .
                 0x2f00  x---0---0---0---0-...--1---0---> hart30
                         |   |   |   |   |      |   |
                 0x2f80  x---0---0---0---0-...--0---1---> hart31
                         <-------- word 0 -------><--- word 1 --->

This patch includes some cleanups to macros/functions.

Fixes: ebf11273220a ("riscv: andes: Rearrange Andes PLICSW to single-bit-per-hart strategy")
Signed-off-by: Yu Chien Peter Lin <peterlin@andestech.com>
Reviewed-by: Randolph <randolph@andestech.com>