commonlib/bsd/helpers: Remove redundancy with libpayload defines

Move STRINGIFY() from coreboot string.h to commonlib/bsd/helpers.h
Remove redundant defines from libpayload.h and libpayloads' standard
headers.

Signed-off-by: Jakub Czapiga <jacz@semihalf.com>
Change-Id: I3263b2aa7657759207bf6ffda750d839e741f99c
Reviewed-on: https://review.coreboot.org/c/coreboot/+/62921
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Tim Wawrzynczak <twawrzynczak@chromium.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>

payloads/libpayload/include/stdlib.h

@@ -34,12 +34,6 @@
 #include <stddef.h>
 #include <string.h>
 
-#define ALIGN(x,a)              __ALIGN_MASK(x,(typeof(x))(a)-1UL)
-#define __ALIGN_MASK(x,mask)    (((x)+(mask))&~(mask))
-#define ALIGN_UP(x,a)           ALIGN((x),(a))
-#define ALIGN_DOWN(x,a)         ((x) & ~((typeof(x))(a)-1UL))
-#define IS_ALIGNED(x,a)         (((x) & ((typeof(x))(a)-1UL)) == 0)
-
 /**
  * @defgroup malloc Memory allocation functions
  * @{