arm64: defconfig: update defconfig for 3.18

This patch enables a few things missing from our defconfig:

  - PCI and MSI, including support for the x-gene host controller
  - BPF JIT
  - SPI, GPIO and MMC for Seattle
  - GPIO for x-gene
  - USB for Juno
  - RTC

It also removes HMC_DRV, which was being built as a module for some
reason.

Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>