rpmsg: glink: do not break from interrupt handler

If receive callback fails, returning error can cause interrupt
handler to exit. if old interrupts have been missed glink may
not read new packets from rx fifo.

Print error message if callback fails but do not return any error
to interrupt handler so that it can continue reading pending data in
rx fifo even if old interrupts were missed and no new interrupt is
coming from remote host.

Change-Id: I1adec1e2ba7337008ecc2d71bf5f96c331a22695
Signed-off-by: Deepak Kumar Singh <deesin@codeaurora.org>