freedreno/registers: Add implicit reg32 for empty arrays

Registers declared as a "naked" array, ie:

  <array offset="0x1234" name="SOME_REG" stride="1" .../>

were not getting register packers generated for them.  Insert an
implicit <reg32> child for them, so the above would be equivalent
to:

  <array offset="0x1234" name="SOME_REG" stride="1" .../>
    <reg32 offset="0" name="REG"/>
  </array>

Signed-off-by: Rob Clark <rob.clark@oss.qualcomm.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/37009>

src/freedreno/registers/gen_header.py

@@ -296,6 +296,7 @@ class Array(object):
 		self.domain = domain
 		self.variant = variant
 		self.parent = parent
+		self.children = []
 		if self.parent:
 			self.name = self.parent.name + "_" + self.local_name
 		else:
@@ -386,6 +387,7 @@ class Reg(object):
 		self.bit_size = bit_size
 		if array:
 			self.name = array.name + "_" + self.name
+			array.children.append(self)
 		self.full_name = self.domain + "_" + self.name
 		if "stride" in attrs:
 			self.stride = int(attrs["stride"], 0)
@@ -729,6 +731,13 @@ class Parser(object):
 		elif name == "reg32":
 			self.current_reg = None
 		elif name == "array":
+			# if the array has no Reg children, push an implicit reg32:
+			if len(self.current_array.children) == 0:
+				attrs = {
+					"name": "REG",
+					"offset": "0",
+				}
+				self.parse_reg(attrs, 32)
 			self.current_array = self.current_array.parent
 		elif name == "enum":
 			self.current_enum = None