usb: xhci: improve Interrupt Management register macros

usb: xhci: improve Interrupt Management register macros

The Interrupt Management register (IMAN), contains three fields:
 - Bit 0:	Interrupt Pending (IP)
 - Bit 1:	Interrupt Enable (IE)
 - Bits 31:2:	RsvdP (Reserved and Preserved)

Currently, there are multiple macros for both the IP and IE fields.
Consolidates them into single mask macros for better clarity and
maintainability.

Comment "THIS IS BUGGY - FIXME - IP IS WRITE 1 TO CLEAR" refers to the
fact that both macros 'ER_IRQ_ENABLE' and 'ER_IRQ_DISABLE' clear the IP bit
by writing '0' before modifying the IE bit. However, the IP bit is actually
cleared by writing '1'. To prevent any regression, this behavior has not
been altered. Instead, when the IE bit is modified, the IP macro is used
explicitly to highlight this "quirk".

Signed-off-by: Niklas Neronin <niklas.neronin@linux.intel.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Link: https://lore.kernel.org/r/20250515135621.335595-16-mathias.nyman@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>