Merged in masayuki2009/nuttx.nuttx/lc823450_smp_improvement (pull request #554)

lc823450 smp improvement

* arch/arm/src/common: Apply irq_spin APIs to modifyregXX

    Replace enter_critical_section with spin_lock_irqsave.
    Replace leave_critical_section with spin_unlock_irqrestore.

    Please see 6150299f as well.

Signed-off-by: Masayuki Ishikawa <Masayuki.Ishikawa@jp.sony.com>

* arch/arm/src/lc823450: Do not use modifyreg32() to enable Mutex.

Signed-off-by: Masayuki Ishikawa <Masayuki.Ishikawa@jp.sony.com>

* arch/arm/src/lc823450: Modify IRQ control for i2s

    Interrupt will be handled on CPU0 with this change.

Signed-off-by: Masayuki Ishikawa <Masayuki.Ishikawa@jp.sony.com>

* arch/arm/src/lc823450: Apply irq_spin APIs to dma/syscontrol/usbdev.

Signed-off-by: Masayuki Ishikawa <Masayuki.Ishikawa@jp.sony.com>

* configs/lc823450-xgevk: Assign CPU1 to lpwork

    This change will improve load balancing for networking with RNDIS.

Signed-off-by: Masayuki Ishikawa <Masayuki.Ishikawa@jp.sony.com>

* drivers/audio/wm8776.c: Improve stability in SMP mode

    Apply irq_spin APIs to improbe performance.
    Repeat to process a message to avoid deadlock.

Signed-off-by: Masayuki Ishikawa <Masayuki.Ishikawa@jp.sony.com>

* configs/lc823450-xgevk: Enable SPINLOCK_IRQ and NXPLAYER in rndis

Signed-off-by: Masayuki Ishikawa <Masayuki.Ishikawa@jp.sony.com>

Approved-by: Gregory Nutt <gnutt@nuttx.org>