toolchain: gcc: Fix separator between directives on same line

The Arm assembler in binutils 2.40 contains a change [1] which affects
how multiple directives on the same line are parsed.

Previously, the following combination of directives parsed successfully:

    .code 32 .balign 4

With binutils 2.40, the following error is now seen:

    Error: junk at end of line, first unrecognised character is `.'

To fix, insert a semicolon after '.code 32', as there already is after
'.thumb'.

[1] https://sourceware.org/git/?p=binutils-gdb.git;a=commitdiff;h=a37854f9162fac592b669eda53f465fc190c9341



Signed-off-by: Peter Hoyes <Peter.Hoyes@arm.com>