i965: Simplify Broadwell's 3DSTATE_MULTISAMPLE sample count handling.
i965: Simplify Broadwell's 3DSTATE_MULTISAMPLE sample count handling.

These enumerations are simply log2 of the number of multisamples shifted
by a bit, so we can calculate them using ffs() in a lot less code.

Suggested by Eric Anholt.

Signed-off-by: Kenneth Graunke <bd2562f754ec92342f93f61c25d731e290a2ffa8@whitecape.org>
Reviewed-by: Eric Anholt <96f164ad4d9b2b0dacf8ebee2bb1eeb3aa69adf1@anholt.net>
Reviewed-by: Anuj Phogat <e2026475996c48f0b97fd37e84129b3912980428@gmail.com>

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