Change in coreboot[master]: src/soc: Remove unused <stdlib.h>

[Felix Held (Code Review)]

Attention is currently required from: Jason Glenesk, Raul Rangel, Anjaneya "Reddy" Chagam, Marshall Dawson, Johnny Lin, Christian Walter, Arthur Heymans, Patrick Rudolph, HAOUAS Elyes, Tim Chu.
Felix Held has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/60617 )

Change subject: src/soc: Remove unused <stdlib.h>
......................................................................

Patch Set 3:

(1 comment)

File src/soc/amd/common/block/acpi/ivrs.c:

https://review.coreboot.org/c/coreboot/+/60617/comment/6a64cb7d_5d0c75a4 
PS3, Line 203: memset
unrelated to the main objective of this patch: not sure where we get the indirect include of string.h which is needed for this. same applies for some other files changed by this patch