target/mips: Include missing "tcg/tcg.h" header

target/mips: Include missing "tcg/tcg.h" header

Commit 83be6b54123 ("Fix MSA instructions LD.<B|H|W|D> on big endian
host") introduced use of typedef/prototypes declared in "tcg/tcg.h"
without including it. This was not a problem because "tcg/tcg.h" is
pulled in by "exec/cpu_ldst.h". To be able to remove this header
there, we first need to include it here in op_helper.c, else we get:

  [222/337] Compiling C object libqemu-mips-softmmu.fa.p/target_mips_msa_helper.c.o
  target/mips/msa_helper.c: In function ‘helper_msa_ld_b’:
  target/mips/msa_helper.c:8214:9: error: unknown type name ‘TCGMemOpIdx’
   8214 |         TCGMemOpIdx oi = make_memop_idx(MO_TE | DF | MO_UNALN,  \
        |         ^~~~~~~~~~~
  target/mips/msa_helper.c:8224:5: note: in expansion of macro ‘MEMOP_IDX’
   8224 |     MEMOP_IDX(DF_BYTE)
        |     ^~~~~~~~~
  target/mips/msa_helper.c:8214:26: error: implicit declaration of function ‘make_memop_idx’ [-Werror=implicit-function-declaration]
   8214 |         TCGMemOpIdx oi = make_memop_idx(MO_TE | DF | MO_UNALN,  \
        |                          ^~~~~~~~~~~~~~
  target/mips/msa_helper.c:8227:18: error: implicit declaration of function ‘helper_ret_ldub_mmu’ [-Werror=implicit-function-declaration]
   8227 |     pwd->b[0]  = helper_ret_ldub_mmu(env, addr + (0  << DF_BYTE), oi, GETPC());
        |                  ^~~~~~~~~~~~~~~~~~~
  cc1: all warnings being treated as errors

Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-Id: <20210207232310.2505283-4-f4bug@amsat.org>