x86/platform/intel-mid: Rename 'spidev' to 'mrfld_spidev'

The current implementation supports only Intel Merrifield platforms. Don't mess
with the rest of the Intel MID family by not registering device with wrong
properties.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20170102092450.87229-1-andriy.shevchenko@linux.intel.com


Signed-off-by: Ingo Molnar <mingo@kernel.org>