mfd: Correct copy and paste mistake in stmpe

When specifying IRQ numbers for the stmpe1601, IRQ defines for the
stmpe24xx were used instead. Fortunately, the defined numbers are
the same, hence why it survived testing. This fix is merely an
aesthetic one.

Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>