target/ppc: Move dquai[q], drint{x,n}[q] to decodetree

target/ppc: Move dquai[q], drint{x,n}[q] to decodetree

Move the following instructions to decodetree:
dquai:   DFP Quantize Immediate
dquaiq:  DFP Quantize Immediate Quad
drintx:  DFP Round to FP Integer With Inexact
drintxq: DFP Round to FP Integer With Inexact Quad
drintn:  DFP Round to FP Integer Without Inexact
drintnq: DFP Round to FP Integer Without Inexact Quad

Signed-off-by: Luis Pires <luis.pires@eldorado.org.br>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20211029192417.400707-13-luis.pires@eldorado.org.br>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>