net: ipa: define COMP_CFG IPA register fields

Create the ipa_reg_comp_cfg_field_id enumerated type, which
identifies the fields for the COMP_CFG IPA register.

Use IPA_REG_FIELDS() to specify the field mask values defined for
this register, for each supported version of IPA.

Use ipa_reg_bit() to build up the value to be written to this
register rather than using the *_FMASK preprocessor symbols.

Remove the definition of the *_FMASK symbols, along with the inline
functions that were used to encode certain fields whose position
and/or width within the register was dependent on IPA version.

Take this opportunity to represent all one-bit fields using BIT(x)
rather than GENMASK(x, x).

Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>