According to the new Armv8-M specification
instructions SQRSHRL and UQRSHLL now have an additional immediate
operand <saturate>. The new assembly syntax is:
SQRSHRL<c> RdaLo, RdaHi, #<saturate>, Rm
UQRSHLL<c> RdaLo, RdaHi, #<saturate>, Rm
where <saturate> can be either 64 (the existing behavior) or 48, in
that case the result is saturated to 48 bits.
The new operand is encoded as follows:
#64 Encoded as sat = 0 #48 Encoded as sat = 1
sat is bit 7 of the instruction bit pattern.
This patch adds a new assembler operand class MveSaturateOperand which
implements parsing and encoding. Decoding is implemented in