Define the fields for the LOCAL_PKT_PROC_CNTXT, COUNTER_CFG, and
IPA_TX_CFG IPA registers for all supported IPA versions.

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

Use ipa_reg_bit() and ipa_reg_encode() to build up the values to be
written to these registers.  Remove the definition of the *_FMASK
symbols as well as proc_cntxt_base_addr_encoded(), because they are
no longer needed.
Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>