MAINTAINERS: add ARM/NXP LPC32XX SoC specific drivers to the section

The change adds a list of files for maintenance under NXP LPC32xx
section, the listed files are NXP LPC32xx SoC series mach files,
DTS files of NXP LPC32xx SoC powered boards and NXP LPC32xx SoC
peripheral drivers, most of the peripheral driver file names match
'lpc32xx' pattern.

Signed-off-by: Vladimir Zapolskiy <vz@mleia.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>