Define the fields for the ENDP_INIT_MODE, ENDP_INIT_AGGR,
ENDP_INIT_HOL_BLOCK_EN, and ENDP_INIT_HOL_BLOCK_TIMER IPA
registers for all supported IPA versions.

Create enumerated types to identify fields for these IPA registers.
Use IPA_REG_STRIDE_FIELDS() to specify the field mask values defined
for these registers, for each supported version of IPA.

Change aggr_time_limit_encode() and hol_block_timer_encode() so they
take an ipa_reg pointer, and use those register's fields to compute
their encoded results.  Have aggr_time_limit_encode() take an IPA
pointer rather than version, to match hol_block_timer_encode().

Use ipa_reg_encode(), ipa_reg_bit(), and ipa_reg_field_max() to
manipulate values to be written to these registers, remove the
definitions of the various inline functions and *_FMASK symbols that
are now no longer used.
Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>