MAINTAINERS: update file entries after arm multi-platform rework and mach-pxa removal

In the work of Arnd's arm multi-platform support, various files in arch/arm
are moved and after the arm mach-pxa removal, only a few files remain to be
not aligned with entries in MAINTAINERS.

These file movements still require adjustments in MAINTAINERS:

  Files in arch/arm/mach-ep93xx/include/mach/ are made local:

    arch/arm/{mach-ep93xx/include/mach/uncompress.h => boot/compressed/misc-ep93xx.h}
    arch/arm/mach-ep93xx/{include/mach => }/ep93xx-regs.h
    arch/arm/mach-ep93xx/{include/mach => }/mach/irqs.h

  Files in arch/arm/mach-vexpress/ are moved to mach-versatile.

Correct the remaining references accordingly after these refactorings.

Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>