MIPS: MSP71xx: Fix build error

MIPS: MSP71xx: Fix build error

When CONFIG_MIPS_MT_SMP is enabled, the following compilation error
occurs:

arch/mips/pmcs-msp71xx/msp_irq_cic.c:134: error: ‘irq’ undeclared

This code clearly never saw a compiler.
The surrounding code suggests, that 'd->irq' was intended, not
'irq'.

This error was found with vampyr.

Signed-off-by: Stefan Hengelein <[email protected]>
Fixes: d7881fbdf866d7d0 ("MIPS: msp71xx: Convert to new irq_chip functions")
Acked-by: Geert Uytterhoeven <[email protected]>
Cc: [email protected]
Cc: [email protected]
Patchwork: https://patchwork.linux-mips.org/patch/8116/
Signed-off-by: Ralf Baechle <[email protected]>