Merge remote-tracking branch 'remotes/xtensa/tags/20190204-xtensa' into staging

target/xtensa: SMP updates and various fixes

- fix CPU wakeup on runstall changes; expose runstall as an IRQ line;
- place mini-bootloader at the BSP reset vector;
- expose CPU core frequency in XTFPGA board FPGA register;
- rearrange access to external interrupts of xtensa cores;
- add MX interrupt distributor and use it on SMP XTFPGA boards;
- add test_mmuhifi_c3 xtensa core variant;
- raise number of CPUs that can be instantiated on XTFPGA boards.

# gpg: Signature made Mon 04 Feb 2019 18:59:32 GMT
# gpg:                using RSA key 2B67854B98E5327DCDEB17D851F9CC91F83FA044
# gpg:                issuer "jcmvbkbc@gmail.com"
# gpg: Good signature from "Max Filippov <filippov@cadence.com>" [unknown]
# gpg:                 aka "Max Filippov <max.filippov@cogentembedded.com>" [full]
# gpg:                 aka "Max Filippov <jcmvbkbc@gmail.com>" [full]
# Primary key fingerprint: 2B67 854B 98E5 327D CDEB  17D8 51F9 CC91 F83F A044

* remotes/xtensa/tags/20190204-xtensa:
  hw/xtensa: xtfpga: raise CPU number limit
  target/xtensa: add test_mmuhifi_c3 core
  hw/xtensa: xtfpga: use MX PIC for SMP
  target/xtensa: add MX interrupt controller
  target/xtensa: expose core runstall as an IRQ line
  target/xtensa: rearrange access to external interrupts
  target/xtensa: drop function xtensa_timer_irq
  target/xtensa: fix access to the INTERRUPT SR
  hw/xtensa: xtfpga: use core frequency
  hw/xtensa: xtfpga: fix bootloader placement in SMP
  target/xtensa: add qemu_cpu_kick to xtensa_runstall

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>