maliit-plugins: Clean up recipe and add missing RDEPENDS

maliit-plugins: Clean up recipe and add missing RDEPENDS

The following errors are only shown when started from console, also there are no visible errors during execution.
Error fixed: QML Image: Error decoding: file:///usr/share/maliit/plugins/org/nemomobile/icon-m-input-methods-shift-lowercase.svg: Unsupported image format

This is unaffected from whether libqtsvg4 is installed or not.

(From meta-openembedded rev: a5ff7a97dd50aaa728fc6fc40402a6535f63ca1d)

Signed-off-by: Samuel Stirtzel <s.stirtzel@googlemail.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
Signed-off-by: Patrick Ohly <patrick.ohly@intel.com>