configs/raspberrypi3_qt5we: set gpu-mem to 200

configs/raspberrypi3_qt5we: set gpu-mem to 200

Qt WebEngine requires more GPU memory than initial setup.

This fixes crashes such as this one.

	#0 0x0000742c63de <unknown>
	#1 0x0000742d0c38 <unknown>
	#2 0x0000749d7bde <unknown>
	#3 0x0000749e3c70 <unknown>
	#4 0x00007530227c <unknown>
	#5 0x000075302480 <unknown>
	#6 0x0000752fb1e4 <unknown>
	#7 0x00007430f878 <unknown>
	#8 0x0000742d5fee <unknown>
	#9 0x0000742d6f44 <unknown>
	#10 0x0000742d721e <unknown>
	#11 0x0000742d7ad6 <unknown>
	#12 0x0000742d57b2 <unknown>
	#13 0x0000742e74f6 <unknown>
	#14 0x0000742f6a74 <unknown>
	#15 0x0000742f41dc <unknown>

	Received signal 6
	#0 0x0000742c63de <unknown>
	#1 0x0000742c66a0 <unknown>
	#2 0x0000725b5d10 <unknown>
	[end of stack trace]
	qml: Render process exited with code 256 (abnormal exit)

Reported-by: Zoltan Gyarmati <mr.zoltan.gyarmati@gmail.com>
Signed-off-by: Gaël PORTAY <gael.portay@savoirfairelinux.com>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>