usb: xhci: simplify Max Scratchpad buffer macros

usb: xhci: simplify Max Scratchpad buffer macros

Max Scratchpad Buffers consist of two bit-fields:
bits 25:21 - Max Scratchpad Buffers High, 5 Most significant bits
bits 27:31 - Max Scratchpad Buffers Low, 5 Least significant bits
Combined they create the Max Scratchpad Buffers value.

Add two new macros, 'HCS_MAX_SP_HI' and 'HCS_MAX_SP_LO', to separately
extract the high and low parts of the Max Scratchpad Buffers. These are
then combined using 'HCS_MAX_SCRATCHPAD' macro. This change simplifies
the code and makes it similar to other split value register macros in the
xhci driver.

Signed-off-by: Niklas Neronin <niklas.neronin@linux.intel.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Link: https://patch.msgid.link/20251119142417.2820519-21-mathias.nyman@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>