soc/intel/fast_spi/Makefile: Rewrite 16mib check for legibility

Perform some cosmetical changes:

* Override the first prerequisite so we can use `$<`.
* Add/remove whitspace to align things (recipe needs to be indented
  by a single tab only).
* We can use shell variables inside double quotes. To make the
  end of the variable name clear, use braces, e.g. "${x}".
  NB. Most of the double quotes are unnecessary. They only change
  the way the script would be failing in case of spurious whitespace.
* Break some lines doing multiple things at once.
* To reduce remaining clutter, put reading numbers into a shell
  function.

And functional changes:

* No need to spawn `cat`, the shell can redirect input as well as
  output (using `<`).
* To read a number from the `fmap_config.h`, we spawned 4 processes
  where a single one can achieve the same. With one exception: GNU
  awk refuses to parse hex numbers by default. Luckily, it turned
  out that we don't need intermediate decimal numbers: Shells can
  do arithmetic with hex values as well.

Change-Id: Ia7bfba0d7864fc091ee6003e09b705fd7254e99b
Signed-off-by: Nico Huber <nico.h@gmx.de>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/51325
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-by: Furquan Shaikh <furquan@google.com>

0 files changed, 0 insertions, 0 deletions