PR tdep/9390: Fix typo on xstorxstormy16-tdep.c

PR tdep/9390: Fix typo on xstorxstormy16-tdep.c

This patch fixes the bug described in PR tdep/9390, which is about a
wrong check in the following code:

    ...

    /* optional copying of args in r2-r7 to r10-r13.  */
    /* Probably only in optimized case but legal action for prologue.  */
    else if ((inst & 0xff00) == 0x4600	/* 46SD   mov rD, rS */
	     && (inst & 0x00f0) >= 0x0020 && (inst & 0x00f0) <= 0x0070
	     && (inst & 0x000f) >= 0x00a0 && (inst & 0x000f) <= 0x000d)
                ^^^^^^^^^^^^^^^^^^^^^^^^^
    ...

This condition will never trigger, and the fix proposed in the bug
(which made sense to me) was to test against 0x000a.  I tried finding
documentation about this target, but couldn't find anything.  I don't
even know if it is still used, but decided to submit the fix anyway.

Tested on my x86_64 Fedora 20 GNU/Linux.

gdb/ChangeLog:
2014-09-16  Sergio Durigan Junior  <sergiodj@redhat.com>

	PR tdep/9390
	* xstorxstormy16-tdep.c (xstormy16_analyze_prologue): Fix possible
	typo when using logical AND to determine instruction type.