x86/intel_rdt: Remove redundant ternary operator on return

The use of the ternary operator is redundant as ret can never be
non-zero at that point. Instead, just return nbytes.

Detected by CoverityScan, CID#1452658 ("Logically dead code")

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Vikas Shivappa <vikas.shivappa@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: kernel-janitors@vger.kernel.org
Link: http://lkml.kernel.org/r/20170808092859.13021-1-colin.king@canonical.com