max8925_power: Remove support for irq bits that do not exist

The max8925 cannot return usb status.  The bits

       [MAX8925_IRQ_VCHG_USB_OVP] = {
               .reg            = MAX8925_CHG_IRQ1,
               .mask_reg       = MAX8925_CHG_IRQ1_MASK,
               .offs           = 1 << 3,
       },
       [MAX8925_IRQ_VCHG_USB_F] =  {
               .reg            = MAX8925_CHG_IRQ1,
               .mask_reg       = MAX8925_CHG_IRQ1_MASK,
               .offs           = 1 << 4,
       },
       [MAX8925_IRQ_VCHG_USB_R] = {
               .reg            = MAX8925_CHG_IRQ1,
               .mask_reg       = MAX8925_CHG_IRQ1_MASK,
               .offs           = 1 << 5,
       },

do not exist in the irq register.

Signed-off-by: Philip Rakity <prakity@marvell.com>
Signed-off-by: Anton Vorontsov <cbouatmailru@gmail.com>