flashrom: switch to building with meson

Added patches to fix meson compilation.

Reworked flashrom.mk to work with meson.

Several minor Makefile cleanups.

Signed-off-by: Rosen Penev <rosenp@gmail.com>

utils/flashrom/patches/030-ppc.patch

@@ -0,0 +1,11 @@
+--- a/hwaccess.c
++++ b/hwaccess.c
+@@ -71,7 +71,7 @@ static inline void sync_primitive(void)
+  * See also https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/memory-barriers.txt
+  */
+ #if IS_PPC // cf. http://lxr.free-electrons.com/source/arch/powerpc/include/asm/barrier.h
+-	asm("eieio" : : : "memory");
++	__asm__ ("eieio" : : : "memory");
+ #elif IS_SPARC
+ #if defined(__sparc_v9__) || defined(__sparcv9)
+ 	/* Sparc V9 CPUs support three different memory orderings that range from x86-like TSO to PowerPC-like