cxl/core/regs: Refactor out functions to count regblocks of given type

cxl/core/regs: Refactor out functions to count regblocks of given type

cxl_find_regblock_instance() counts the number of instances of a register
block as a side effect of searching through all available register blocks.
cxl_count_regblock() throws away that work and recounts all the register
blocks by asking cxl_find_regblock_instance() to redo work it has
already done until it finally returns an error, that is needlessly
wasteful.

Let cxl_count_regblock() leverage the counting that
cxl_find_regblock_instance() already does by passing in a sentinel value
(CXL_INSTANCES_COUNT) that triggers the count to be returned.

[ davej: Updated to more concise commit log supplied by djbw ]
[ davej: Fix up checkpatch formatting warnings ]

Signed-off-by: Huaisheng Ye <huaisheng.ye@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Link: https://patch.msgid.link/20250115152600.26482-2-huaisheng.ye@intel.com
Signed-off-by: Dave Jiang <dave.jiang@intel.com>