target/nios2: Use hw/registerfields.h for CR_TLBACC fields

target/nios2: Use hw/registerfields.h for CR_TLBACC fields

Retain the helper macros for single bit fields as aliases to
the longer R_*_MASK names.  Use FIELD_EX32 and FIELD_DP32
instead of manually manipulating the fields.

Since we're rewriting the references to CR_TLBACC_IGN_* anyway,
we correct the name of this field to IG, which is its name in
the official CPU documentation.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20220421151735.31996-28-richard.henderson@linaro.org>