hw/ppc/ppc440_uc: Remove dead l2sram_update_mappings()

hw/ppc/ppc440_uc: Remove dead l2sram_update_mappings()

Apparently l2sram_update_mappings() bit-rotted over time,
when defining MAP_L2SRAM we get:

  hw/ppc/ppc440_uc.c:83:17: error: no member named 'isarc' in 'struct ppc4xx_l2sram_t'
      if (l2sram->isarc != isarc ||
          ~~~~~~  ^
  hw/ppc/ppc440_uc.c:84:18: error: no member named 'isacntl' in 'struct ppc4xx_l2sram_t'
          (l2sram->isacntl & 0x80000000) != (isacntl & 0x80000000)) {
           ~~~~~~  ^
  hw/ppc/ppc440_uc.c:85:21: error: no member named 'isacntl' in 'struct ppc4xx_l2sram_t'
          if (l2sram->isacntl & 0x80000000) {
              ~~~~~~  ^
  hw/ppc/ppc440_uc.c:88:50: error: no member named 'isarc_ram' in 'struct ppc4xx_l2sram_t'
                                          &l2sram->isarc_ram);
                                           ~~~~~~  ^
  hw/ppc/ppc440_uc.c:93:50: error: no member named 'isarc_ram' in 'struct ppc4xx_l2sram_t'
                                          &l2sram->isarc_ram);
                                           ~~~~~~  ^
  hw/ppc/ppc440_uc.c:96:17: error: no member named 'dsarc' in 'struct ppc4xx_l2sram_t'
      if (l2sram->dsarc != dsarc ||
          ~~~~~~  ^
  hw/ppc/ppc440_uc.c:97:18: error: no member named 'dsacntl' in 'struct ppc4xx_l2sram_t'
          (l2sram->dsacntl & 0x80000000) != (dsacntl & 0x80000000)) {
           ~~~~~~  ^
  hw/ppc/ppc440_uc.c:98:21: error: no member named 'dsacntl' in 'struct ppc4xx_l2sram_t'
          if (l2sram->dsacntl & 0x80000000) {
              ~~~~~~  ^
  hw/ppc/ppc440_uc.c:100:52: error: no member named 'dsarc' in 'struct ppc4xx_l2sram_t'
              if (!(isacntl & 0x80000000) || l2sram->dsarc != isarc) {
                                             ~~~~~~  ^
  hw/ppc/ppc440_uc.c:103:54: error: no member named 'dsarc_ram' in 'struct ppc4xx_l2sram_t'
                                              &l2sram->dsarc_ram);
                                               ~~~~~~  ^
  hw/ppc/ppc440_uc.c:111:54: error: no member named 'dsarc_ram' in 'struct ppc4xx_l2sram_t'
                                              &l2sram->dsarc_ram);
                                               ~~~~~~  ^

Remove that dead code.

Reviewed-by: BALATON Zoltan <balaton@eik.bme.hu>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>