x86/platform/uv: Fix missing checks of kcalloc() return values

Handle potential errors returned from kcalloc().

 [ bp: rewrite commit message. ]

Signed-off-by: Kangjie Lu <kjlu@umn.edu>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Andrew Banman <abanman@hpe.com>
Cc: Andy Shevchenko <andy@infradead.org>
Cc: Colin Ian King <colin.king@canonical.com>
Cc: Darren Hart <dvhart@infradead.org>
Cc: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Mike Travis <mike.travis@hpe.com>
Cc: Nicolai Stange <nstange@suse.de>
Cc: pakki001@umn.edu
Cc: platform-driver-x86@vger.kernel.org
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Varsha Rao <rvarsha016@gmail.com>
Cc: x86-ml <x86@kernel.org>
Link: https://lkml.kernel.org/r/20190325202924.4624-1-kjlu@umn.edu