Change in coreboot[master]: soc/intel/common/../car: Calculate SF Mask#1 based on MSR 0xc87

[Tim Wawrzynczak (Code Review)]

Attention is currently required from: Furquan Shaikh, Subrata Banik, Nick Vaccaro, EricR Lai.
Tim Wawrzynczak has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/51374 )

Change subject: soc/intel/common/../car: Calculate SF Mask#1 based on MSR 0xc87
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Patch Set 8:

(1 comment)

File src/soc/intel/common/block/cpu/car/cache_as_ram.S:

https://review.coreboot.org/c/coreboot/+/51374/comment/a02545f5_017653d0 
PS8, Line 532: mov	%al, %cl
             : 	mov	$0x01, %eax
             : 	shl	%cl, %eax
             : 	subl	$0x01, %eax /* contains ((1 << SFWayCnt) - 1) */
             : 	mov	%bl, %cl
             : 	mov	$0x01, %ebx
             : 	shl	%cl, %ebx
             : 	subl	$0x01, %ebx /* contains ((1 << data_ways) - 1) */
             : 	sub	%ebx, %eax /* contains SF mask */
> subl	%ecx, %edi       /* ecx == SFWayCnt - data_ways */ […]

Oops, yes, I mixed up the order of registers in that line, you figured out what I meant 😉 Right, with this sequence, there are fewer instructions and `ebx` doesn't need to be saved/restored