ihex: Share code between ihex_validate_fw() and ihex_next_binrec()

ihex: Share code between ihex_validate_fw() and ihex_next_binrec()

Convert both ihex_validate_fw() and ihex_next_binrec() to use a helper
function to calculate next record offest. This way we only have one
place implementing next record offset calculation logic. 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>