net: mvpp2: prs: Drop unions representing TCAM and SRAM entries

PPv2's Header Parser use some large TCAM and SRAM entries, that are
duplicated in software so that we can write them to hardware only when
we are done modifying them.

Currently, PPv2 uses a union containing arrays of u32 and u8 to represent
these entries, to facilitate byte per byte access. This representation is
broken when we want to support big endian, and this makes the code
confusing to read.

This patch drops the union, and simply stores the TCAM and SRAM entries
as u32 arrays, each entry corresponding to a 32-bit register.

Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Signed-off-by: David S. Miller <davem@davemloft.net>