tools/firmware/ihex2fw: Replace explicit alignment with ALIGN

tools/firmware/ihex2fw: Replace explicit alignment with ALIGN

(X + 3) & ~3 is the same as ALIGN(X, 4), so replace all of the
instances of the formwer in the code with the latter. While at it,
introduce a helper variable 'record_size' to avoid duplicating length
calculatin code. No functional change intended.

Cc: Chris Healy <cphealy@gmail.com>
Cc: Kyle McMartin <kyle@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-kernel <linux-kernel@vger.kernel.org>
Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>